Question

sin18°×cos72°+cos18°×sin72° how to solve this problem​

Answer 1

Answer:

$\sin(18) \times \cos(72) + \cos(18) \times \sin(72) \\ \sin(90 - 18) \times \cos(72) + \cos(90 - 18) \times \sin(72) \\ \sin(72) \times \sin(72) + \cos(72) \times \cos(72) = 1$ (sin A+ cos A=1)

thanks my answer❤

Answer 2

Answer:

We Have : sin18°×cos72°+cos18°×sin72°

By this time we know that , sin(90-x) = cosx & cos(90-x) = sinx

=> sin18°× cos(90-18) + cos18° × sin(90-18)

=>sin18°(sin18°) + cos18°(cos18°)

=> $sin^218+cos^218=1$