∴∠CAB=30`

AB = AC

∴△ABC is an isosceles triangle

∴∠B=∠ACB

∠∠b+∠ACB+∠CAB = 180 '

∴∠B=( 180-30)/2=75`

2.∠∠D =∠ACD

∫△ACD is isosceles△

∴AD=AC=6

∴ centerline length =(6+9)/2=7.5

3.∵BE//DC and be =DC

∴ Quadrilateral BECD is a parallelogram.

∴ BD=CE

∵ABCD is an isosceles trapezoid.

∴BD=AC

∴AC=CE

△ CAE is an isosceles triangle.