HELP: Area of shadow

HELP: Daughter's Math question, find the area of shadow, please show your solution in detail. thanks

 

所有跟帖： 

• 可不可以这样（我没法画图） -眼镜- ♂ (679 bytes) () 05/22/2019 postreply 20:45:26

• 我觉得最好的办法是用autocad 画一下，然后点一下阴影，面积就出来了 -千里一盏灯- ♂ (0 bytes) () 05/22/2019 postreply 22:07:20

• 用这个定理试试看？ -greenoasis- ♀ (2924 bytes) () 05/23/2019 postreply 05:37:32

• thanks all so much, my daughter is in elementary school, maybe " -nirvana_wander- ♂ (0 bytes) () 05/23/2019 postreply 08:17:18

• Elementary? Calculator? EXACT Answer? Approximate? -dr_yin- ♂ (0 bytes) () 05/23/2019 postreply 08:52:03

• 用三角形面积公式不难求出A点坐标（16/5， -12/5）不过扇形面积就要牵扯到反三角函数了。想不到小学知识怎么做。 -光猜不想- ♂ (279 bytes) () 05/24/2019 postreply 15:30:05