The first part is to find the length SQ which is equal to SP.
Use the sine rule.
SQ/sin 65 = (SQ - 1)/Sin50
(sin50)/(sin 65) = (SQ-1)/SQ
0.8452(SQ) = SQ-1
0.1547SQ = 1
SQ = 6.46
The formula to apply here is:
Area=1/2(SQ)(SQ)sin50
= 0.5 × 6.46 × 6.46 × sin50
= 15.984