梯形的面积公式是S=1/2(a+b)h.已知S=30,a=6,h=4,求b;S=60,a=8,b=12,求h

问题描述:

梯形的面积公式是S=1/2(a+b)h.已知S=30,a=6,h=4,求b;S=60,a=8,b=12,求h

将S=30,a=6,h=4代入得30=0.5(6+b)4 h=15
将S=60,a=8,b=12代入得60=0.5(8+12)h h=12

a=9.....b=6

2S=(a+b)h
2S/h=a+b
b=2S/h-a
b=9
h=2S/(a+b)
h=6