Answer:

Step-by-step Explanation:
The Pythagorean identity is given by:

Since
(and
is in the 1st quadrant, where both sine and cosine are positive), we can use this information to find
.
Let
:

Now, solve for
:

Subtract
from both sides:

Take the square root of both sides:

Since
is in the 1st quadrant, where
is positive, we take the positive square root:

Now, simplify if possible:

Since
:



So,
