设梯形上底长为A,下底长为B,高为H,面积为S
问题描述:
设梯形上底长为A,下底长为B,高为H,面积为S
(1)A=根号24,B=根号2,H=根号6,求S
(2)A=根号5,B=根号20,H=根号5,求S
(3)A=2根号3,B=3根号,H=4根号3,求S
答
(1)A=根号24,B=根号2,H=根号6,求S
S = (A+B)H/2
= (√24 +√2)√6 / 2
= (12 + 2√2) / 2
= 6 + √2
(2)A=根号5,B=根号20,H=根号5,求S
S = (A+B)H/2
= (√5 +√20)√5 / 2
= (5 + 10) / 2
= 7.5
(3)A=2根号3,B=3根号,H=4根号3,求S
S = (A+B)H/2
= (2√3 +3√3) × 4√3 / 2
= (2√3 +3√3) × 2√3
= 12 + 18
= 30刚刚发现最后一题题目错了。。A=2根号3,B=3根号12,H=4根号3,求S(3)A=2根号3,B=3根号12,H=4根号3,求SS = (A+B)H/2 = (2√3 +3√12) × 4√3 / 2 = (2√3 +3√12) × 2√3 = 12 + 36 = 48