Octagon Interior & Exterior Angle Sum Theorems

Octagon Interior & Exterior Angle Sum Theorems
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2015-10-29 19:38
This GeoGebra applet informally illustrates to students that the sum of the measures of the interior angles of an octagon is 1080 degrees, and that the sum of the measures of the exterior angles is 360 degrees. It involves key mathematical concepts such as the interior and exterior angle sum theorems of polygons. Using commands like Ray, Circle, Intersect, Segment, etc., students can dynamically explore the geometric properties of the octagon. Suitable for middle school and above students to learn polygon geometry.

GeoGebra Commands & Parameters

  1. Ray(S_1, D) → i_5
  2. Circle(D, 1.5) → k
  3. Intersect(k, i_5) → U_1, V_1
  4. Ray(D, A_1) → a_3
  5. Intersect(k, a_3, 1) → D_1
  6. Segment(C, A_1) → i_3
  7. Circle(C, 1.5) → h
  8. Intersect(h, i_3) → L,
  9. Ray(C, D) → c
  10. Intersect(h, c, 1) → P
  11. Ray(A, B) → a
  12. Ray(B, C) → b
  13. Ray(E, A) → e
  14. Circle(A, 1.5) → f
  15. Circle(B, 1.5) → g
  16. Circle(E, 1.5) → p
  17. Segment(C, A) → i
  18. Segment(C, E) → j
  19. Intersect(f, a, 1) → F
  20. Intersect(f, i, 1) → G
  21. Intersect(f, e, 1) → H
  22. Intersect(f, e, 2) → I
  23. Intersect(p, e) → J,
  24. Intersect(p, j) → K,
  25. Intersect(k, c, 2) → O
  26. Intersect(h, j, 1) → Q
  27. Intersect(h, i, 1) → R
  28. Intersect(h, b, 1) → S
  29. Intersect(g, a, 2) → T
  30. Intersect(g, b, 1) → U
  31. Intersect(g, a, 1) → V
  32. CircleSector(A, F, G) → q
  33. CircleSector(A, G, H) → r
  34. CircleSector(B, U, V) → s
  35. CircleSector(C, Q, R) → c_1
  36. CircleSector(C, R, S) → d_1
  37. Intersect(k, c, 1) → W
  38. CircleSector(E, J, K) → h_1
  39. CircleSector(A, I, F) → p_1
  40. CircleSector(B, T, U) → q_1
  41. Intersect(h, b, 2) → Z
  42. Vector(A, B) → u
  43. Vector(C, B) → v
  44. Vector(E, D) → w
  45. Vector(C, D) → u_1
  46. Vector(C, E) → v_1
  47. Vector(A, E) → w_1
  48. Translate(q, u) → q'
  49. Translate(d_1, v) → s_1
  50. Mirror(s_1, B) → t_1
  51. Dilate(A, If[0 < l ≤ 1, 1 - l, 0], B) → A'
  52. Dilate(C, If[0 < l ≤ 1, 1 - l, 0], B) → C'
  53. Dilate(A, If[1 < l ≤ 2, 2 - l, 0], E) → A'_1
  54. Dilate(C, If[1 < l ≤ 2, 2 - l, 0], E) → C'_1
  55. Dilate(C, If[2 < l ≤ 3, 3 - l, 0], D) → C'_2
  56. Dilate(E, If[2 < l ≤ 3, 3 - l, 0], D) → E'
  57. Vector(A, B) → a_1
  58. Vector(C, C') → b_1
  59. Vector(A, A'_1) → i_1
  60. Vector(E, E') → j_1
  61. Vector(C, C'_2) → l_1
  62. Vector(C, C'_1) → m_1
  63. Translate(d_1, b_1) → c_2
  64. Translate(r, i_1) → r'_1
  65. Translate(r, w_1) → r'_2
  66. Translate(c_1, v_1) → f_2
  67. Translate(c_1, m_1) → g_2
  68. CircleSector(C, P, L) → t
  69. Translate(t, u_1) → t'
  70. Translate(t, l_1) → t'_1
  71. Translate(q, a_1) → r'
  72. Translate(d_1, b_1) → h_2
  73. If(0 < l < 1, Rotate[h_2, ((l * 180))°, C']) → k_2
  74. Vector(A, A') → n_1
  75. Translate(q, n_1) → q'_1
  76. Mirror(r'_2, E) → p_2
  77. If(1 < l < 2, Rotate[r'_1, (((l - 1) * 180))°, A'_1]) → q_2
  78. Segment(E, C) → i_2
  79. Vector(D, C) → u_2
  80. Vector(E, C) → v_2
  81. Vector(A, C) → w_2
  82. Vector(B, C) → l_2
  83. Dilate(B, If[0 < o < 1, 1 - o, 0], C) → B'
  84. Dilate(A, If[1 < o < 2, 2 - o, 0], C) → A'_2
  85. Dilate(E, If[2 < o < 3, 3 - o, 0], C) → E'_1
  86. Dilate(D, If[3 < o < 4, 4 - o, 0], C) → D'
  87. Vector(B, B') → m_2
  88. Vector(A, A'_2) → n_2
  89. Vector(E, E'_1) → s_2
  90. Vector(D, D') → t_2
  91. Translate(q_1, m_2) → c_3
  92. Translate(q_1, l_2) → d_3
  93. Translate(p_1, w_2) → e_3
  94. If(1 < o < 2, Translate[p_1, n_2]) → h_3
  95. Ray(A_1, E) → b_3
  96. Circle(A_1, 1.5) → q_3
  97. Intersect(q_3, i_3) → M,
  98. Intersect(q_3, b_3, 1) → N
  99. Intersect(q_3, a_3, 2) → B_1
  100. Intersect(k, c, 2) → C_1
  101. Intersect(k, c, 1) → E_1
  102. CircleSector(C, L, Q) → d
  103. Intersect(p, b_3, 1) → F_1
  104. Intersect(p, i_2) → G_1,
  105. CircleSector(E, G_1, N) → e_1
  106. Dilate(E, If[2 < l < 3, 3 - l, 0], A_1) → E'_2
  107. Dilate(C, If[2 < l < 3, 3 - l, 0], A_1) → C'_3
  108. Dilate(C, If[3 < l < 4, 4 - l, 0], D) → C'_4
  109. Dilate(A_1, If[3 < l < 4, 4 - l, 0], D) → H_1
  110. Vector(E, A_1) → f_1
  111. Vector(C, A_1) → g_1
  112. Translate(e_1, f_1) → k_1
  113. Translate(d, g_1) → d'
  114. Vector(E, E'_2) → a_2
  115. Vector(C, C'_3) → b_2
  116. Translate(e_1, a_2) → d_2
  117. Translate(d, b_2) → d'_1
  118. Rotate(d_2, If[2 < l < 3, (((l - 2) * 180))°, 0], E'_2) → e_2
  119. Mirror(k_1, A_1) → r_2
  120. CircleSector(A_1, N, M) → f_3
  121. Intersect(q_3, a_3, 1) → I_1
  122. CircleSector(A_1, M, I_1) → g_3
  123. CircleSector(D, D_1, E_1) → k_3
  124. Vector(C, D) → j_2
  125. Vector(A_1, D) → u_3
  126. Translate(g_3, u_3) → p_3
  127. Translate(t, j_2) → t'_2
  128. Mirror(p_3, D) → r_3
  129. Vector(A_1, H_1) → v_3
  130. Vector(C, C'_4) → w_3
  131. Translate(g_3, v_3) → s_3
  132. Translate(t, w_3) → t'_3
  133. Rotate(s_3, If[3 < l < 4, (((l - 3) * 180))°, 0], H_1) → t_3
  134. Intersect(p, b_3, 2) → J_1
  135. Polygon(A, B, C) → poly1, c_4, a_4, b_4
  136. Polygon(A, C, E) → poly2, e_4, a_5, c_5
  137. Polygon(E, C, A_1) → poly3, a_6, e_5, c_6
  138. Polygon(A_1, C, D) → poly4, d_4, a_7, c_7
  139. Intersect(p, e, 1) → L_1
  140. CircleSector(E, J_1, L_1) → f_4
  141. CircleSector(A_1, B_1, N) → g_4
  142. Vector(E, C) → j_3
  143. Vector(A_1, C) → l_3
  144. Vector(D, C) → m_3
  145. Translate(f_4, j_3) → k_4
  146. Translate(g_4, l_3) → p_4
  147. CircleSector(D, V_1, D_1) → h_4
  148. Translate(h_4, m_3) → q_4
  149. Dilate(E, If[2 < o < 3, 3 - o, 0], C) → E'_3
  150. Dilate(A_1, If[3 < o < 4, 4 - o, 0], C) → M_1
  151. Dilate(D, If[4 < o < 5, 5 - o, 0], C) → D'_1
  152. Vector(E, E'_3) → n_3
  153. Vector(A_1, M_1) → u_4
  154. Vector(D, D'_1) → v_4
  155. If(2 < o < 3, Translate[f_4, n_3]) → r_4
  156. If(3 < o < 4, Translate[g_4, u_4]) → s_4
  157. If(4 < o < 5, Translate[h_4, v_4]) → t_4
  158. Ray(C, N_1) → i_4
  159. Ray(N_1, D) → l_4
  160. Circle(N_1, 1.5) → d_5
  161. Intersect(d_5, i_4, 2) → K_1
  162. Intersect(d_5, l_4, 1) → O_1
  163. Intersect(d_5, i_4, 1) → P_1
  164. Intersect(h, i_4, 1) → Q_1
  165. Intersect(k, l_4, 1) → R_1
  166. Dilate(D, If[4 < l < 5, 5 - l, 0], N_1) → D'_2
  167. Dilate(C, If[4 < l < 5, 5 - l, 0], N_1) → C'_5
  168. Vector(C, N_1) → w_4
  169. Vector(D, N_1) → j_4
  170. Vector(D, D'_2) → m_4
  171. Vector(C, C'_5) → n_4
  172. Ray(N_1, S_1) → b_5
  173. Segment(D, C) → j_5
  174. Intersect(d_5, b_5) → T_1,
  175. Dilate(D, If[5 < l < 6, 6 - l, 0], S_1) → D'_3
  176. Dilate(N_1, If[5 < l < 6, 6 - l, 0], S_1) → W_1
  177. Vector(D, D'_3) → u_5
  178. Vector(N_1, W_1) → v_5
  179. Vector(D, S_1) → w_5
  180. Vector(N_1, S_1) → m_5
  181. Circle(S_1, 1.5) → r_6
  182. Intersect(r_6, i_5, 1) → Z_1
  183. Intersect(r_6, b_5) → A_2, B_2
  184. Polygon(A, B, C, N_1, S_1, D, A_1, E) → poly7, a_8, b_6, c_9, n_7, s_7, d_8, a_9, e_8
  185. CircleSector(C, Z, Q_1) → r_1
  186. CircleSector(W_1, B_2, Z_1) → h_7
  187. CircleSector(N_1, K_1, T_1) → k_7
  188. Vector(W_1, C) → u_6
  189. Vector(N_1, C) → v_6
  190. Translate(h_7, u_6) → p_7
  191. Vector(D, C) → w_6
  192. Translate(h_4, w_6) → q_7
  193. Dilate(W_1, If[5 < o < 6, 6 - o, 0], C) → C_2
  194. Vector(W_1, C_2) → i_6
  195. Translate(h_7, i_6) → r_7
  196. Dilate(N_1, If[6 < o < 7, 7 - o, 0], C) → D_2
  197. Vector(N_1, D_2) → j_6
  198. Translate(k_7, j_6) → t_7
  199. Vector(N_1, C) → l_6
  200. Translate(k_7, l_6) → f_8
  201. Ray(C, D) → m_6
  202. Ray(C, A_1) → b_7
  203. Ray(C, E) → i_7
  204. Point(i_7) → E_2
  205. Point(b_7) → F_2
  206. Point(m_6) → G_2
  207. Ray(E, E_2) → j_7
  208. Ray(A_1, F_2) → l_7
  209. Ray(D, G_2) → m_7
  210. Segment(C, S_1) → l_5
  211. Intersect(k, i_5, 1) → H_2
  212. Intersect(d_5, b_5, 1) → I_2
  213. CircleSector(N_1, I_2, P_1) → g_5
  214. Intersect(r_6, l_5) → J_2,
  215. Intersect(k, j_5) → K_2,
  216. CircleSector(S_1, Z_1, J_2) → f_7
  217. CircleSector(S_1, J_2, A_2) → f_5
  218. CircleSector(D, K_2, H_2) → h_5
  219. Intersect(h, j_5) → L_2,
  220. Intersect(h, l_5) → M_2,
  221. Intersect(h, i_4) → N_2,
  222. CircleSector(C, M_2, L_2) → k_5
  223. CircleSector(C, N_2, M_2) → p_5
  224. Dilate(D, If[4 < l < 5, 5 - l, 0], S_1) → D'_4
  225. Dilate(C, If[4 < l < 5, 5 - l, 0], S_1) → C'_6
  226. Vector(D, S_1) → n_5
  227. Vector(C, S_1) → q_5
  228. Translate(h_5, n_5) → r_5
  229. Mirror(r_5, S_1) → s_5
  230. Vector(D, D'_4) → t_5
  231. Translate(h_5, t_5) → d_6
  232. Rotate(d_6, If[4 < l < 5, (((l - 4) * 180))°, 0], D'_4) → e_6
  233. Translate(k_5, q_5) → f_6
  234. Vector(C, C'_6) → g_6
  235. Translate(k_5, g_6) → h_6
  236. Dilate(S_1, If[5 < l < 6, 6 - l, 0], N_1) → O_2
  237. Dilate(C, If[5 < l < 6, 6 - l, 0], N_1) → C'_7
  238. Vector(C, N_1) → k_6
  239. Translate(p_5, k_6) → p_6
  240. Vector(C, C'_7) → n_6
  241. Translate(p_5, n_6) → q_6
  242. Vector(S_1, N_1) → s_6
  243. Translate(f_5, s_6) → t_6
  244. Mirror(t_6, N_1) → d_7
  245. Vector(S_1, O_2) → u_7
  246. Translate(f_5, u_7) → e_7
  247. Rotate(e_7, If[5 < l < 6, (((l - 5) * 180))°, 0], O_2) → g_7
  248. Ray(C, S_1) → b_8
  249. Polygon(D, C, S_1) → poly5, s_8, d_9, c_8
  250. Polygon(S_1, C, N_1) → poly6, n_8, s_9, c_{10}