# Math Help - [SOLVED] Trignometry Help

1. ## [SOLVED] Trignometry Help

Question:
In each of the following cases find the least positive value of $\alpha$ for which:
$\cos ( \alpha-\theta )^o = \sin \theta^o$

Attempt:
Don't know how to get the value of $\alpha$

2. Hello,

Once again use the formula :

cos(a-b)=cos(a)cos(b)+sin(a)sin(b)

So you will have to find $\alpha$ such as $\cos(\alpha)=0$ and $\sin(\alpha)=1$ as this relation has to be true for any $\theta$