Question

1
Sin ²20 t Sin²40 +SPn ²50 t Sin² 74
then n = 2​

Answer 1

Step-by-step explanation:

sine(x)=cos(x−90) [1]

cos(x)=cos(−x) [2]

sin2(x)+cos2(x)=1 [3]

From [1], sin(70)=cos(−20)

From [2], cos(−20)=cos(20)

So, sin(70)=cos(20)

From [3], sin2(70)+sin2(20)

=cos2(20)+sin2(20)=1