Jika p-q= cosA dan [tex] \sqrt{2pq} [/tex]= sinA maka p²+q²=

p-q= cosA
p^2 + q^2 - 2pq = cos^2 A

akar(2pq) = sin A
2pq = sin^2 A

p^2 + q^2 - 2pq + 2pq = cos^2 A + sin^2 A
p^2 + q^2 = 1

Trigonometri

√(2pq) = sin A
[ √(2pq) ]² = sin² A
2pq  = sin² A

p - q = cos A
(p-q)² = cos² A

p² + q²  = cos² A + 2 pq
p² + q² = cos² A  + sin² A
p² + q² = 1