no. 14&15 gimana caranya?

begini jawabanku^^ coba dicek dulu siapa tau aku salah itung

trigonometri
14
misal p =  (sin A + cos B)
dan q = (sin A - cos B)
p+ q = 2 sin A
pq = sin² A - cos² A
p²+q² =(p + q)² -2 pq
p²+q²  = (2 sin A)² - 2(sin² A - cos² A)
p²+q² = 4 sin² A - 2 sin² A + 2 cos² A
p²+q² = 2 sin² A + 2 cos² A = 2 ( sin² A + cos² A)
p²+q² = 2(1) = 2

15.
cos R = QR/PR
PR = QR/ cos 45
PR  = 10 / (1/2 √2)
PR = 20/√2
PR =20√2 /(2)
PR = 10√2