16. 已知∆ABC為正三角形,其邊長為 8,請問∆ABC面積為何?
(A)
【用戶】Jiunndar Yeh
【年級】幼兒園下
【評論內容】因△ABC邊長為8,即AB = BC = 8過A點做BC上的高,此時BD = CD = BC/2 = 4AD = √(AB2 - BD2) = √(82 - 42) = √(64 - 16) = √48 = √(42 * 3) = 4√3故△ABC面積 = 1/2 * BC * AD = 1/2 * 8 * 4√3 = 4 * 4√3 = 16√3 ...選項(C)正確