GEOOOOMETRY!!!!!....Angled Perimeter
posted by HELP ME...uRGENT! .
ABCD is a quadrilateral with ∠ADC=∠ACD, ∠ACB=∠ABC and CD=7. If triangles ADC and ABC have perimeter 51 and 59, respectively, what is the value of BC?

∆ACD and ∆ACB are isosceles
So, AD=AC and AB=AC
AC = (517)/2 = 22
So, BC=592222 = 15