Answer:
Step-by-step explanation:
An acute triangle (or acute-angled triangle) is a triangle with three acute angles (less than 90°). An obtuse triangle (or obtuse-angled triangle) is a triangle with one obtuse angle (greater than 90°) and two acute angles.
Is it asking for the perimeter of a square?
I suppose you mean to have the entire numerator under the square root?

We can use a trigonometric substitution to start:

Then for
,
; for
,
. So the integral is equivalent to

We can write

so the integral becomes
