Question

Please someone help me...​

Answer 1

Take a look at the explanation below. It proves that 'x / y = cot(θ + β / 2)' using a different method.

Answer 2

Explanation:

x cos θ + y sin θ = x cos β + y sin β

Let's say x = cos A, and y = sin A.

cos A cos θ + sin A sin θ = cos A cos β + sin A sin β

Use angle sum formula.

cos(A − θ) = cos(A − β)

A − θ = ±(A − β)

A − θ = β − A

2A = θ + β

A = (θ + β) / 2

cot A = cot((θ + β) / 2)

x/y = cot((θ + β) / 2)