Area of a Triangle Formula is
A = 1/2 abSINc
Label the sides of the triangle PR = 2x = a PQ = x = b
1/2 (x) 2x (x) x (x) SINc = A = x2 SINc
Rearrange the equation to give
(squared root) { A = x { SINc
QP^R = 30, thereforeQP^R = SIN(30) = 1/2
A divided by 1/2 = 2A
Therefore x = (squared root){2A