In this solution the angle of sin and cos is not equal so why theta is equal to pie - Maths - Complex Numbers and Quadratic Equations

Question

In this solution the angle of sin and cos is not equal so why theta
is equal to pie As you can see sin theta is equal to 0? and cos
theta is equal to 90? So why pie became the solution

Maria Sybil · Answer

Cos 180=-1
Sin 180=0
So theta= pie

In this solution the angle of sin and cos is not equal so why theta is equal to pie. As you can see sin theta is equal to 0? and cos theta is equal to 90?. So why pie became the solution.