Question

梯形的上底长为（3n+4m）cm,下底长为（2m+5n）cm,它的高为（m+2n）cm,求此梯形的面积.

Answer 1

此梯形的面积

S=[（3n+4m）+（2m+5n）]*（m+2n）/2

=(8n+6m)*(m+2n)/2

=(4n+3m)(m+2n)

=3m^2+10mn+8n^2.