tolongin bro mudah kok soalnya

^ = pangkat
Misal m^2 = a dan n^2= b
Cos Q = x/h = (a-b)/(a+b)

sesuai dgn hukum phytagoras
h = (√x^2 + y^2)
h^2 = x^2 + y^2
(a+b)^2 = (a-b)^2 + y^2
a^2 + 2ab + b^2= a^2-2ab +b^2 + y^2
a^2 -a^2 + 2ab+2ab +b^2 -b^2 = y^2
4ab = y^2
√4ab = y
y = 2√ab

Tadi kan a=m^2 dan b=n^2 maka
y = 2√ab = 2(√m^2.n^2)
y = 2mn

Sin Q = y/h = 2mn/(m^2 + n^2)

sorry klo salah