在圖中，PORS是一些梯形，QR=6cm,上∠PSR=60度
∠PQR=∠SPR=90度。證明PQRS的面積為42開方3cm
幫我計下，我明天要交
2007-02-08 3:42 am
回答 (1)
2007-02-08 4:49 am
✔ 最佳答案
In the figurehttp://i86.photobucket.com/albums/k120/kr9497/123.jpg,
∠PRS = 30°
PQ // RS
so ∠QRP = 90° - 30° = 60
tan∠PRQ = tan 60° = PQ/QR
PQ = 6√3
cos∠PRQ = cos 60° = QR/PR
PR = 12
sin∠PSR = sin 60° = PR/RS
RS = 8√3
So the area = (8√3+6√3) x 6 / 2
=14√3 x 3
= 42√3 cm²
收錄日期: 2021-04-23 16:39:23
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070207000051KK03199