Question

ABCD is a trapizoid of bases [AB] and [DC], M and N are the midpoint of [AD] and [BC] if DC=11cm and MN=9cm then AB=

Answer 1

`AB = 7`

Explanation:

Given

`DC = 11`

`MN = 9`

Required

Find AB

Since MN is the midpoint, then:

`MN = (1)/(2)(AB + DC)`

`9 = (1)/(2)(AB + 11)`

Multiply by 2

`2 * 9 = (1)/(2)(AB + 11)*2`

`18 = AB + 11`

`AB = 18 - 11`

`AB = 7`