60°
step-by-step explanation:
the measure angle of c in an isosceles triangle abc is 60° because in isosceles triangle,the measures of all the angles is 60°.
let pq = qr = rs = x, and xz = y and zu = z.
if the horizontal lines are parallel, then corresponding segments are in proportion:
substitute:
therefore 3 = y = z.
xu = y + z → xu = 3 + 3 = 6