# Angle/Area problem

#### 12345786332

##### New member
The fourth part of the question (d), I can't find the value for the angle. Tried everything.

Staff member

#### 11199264

##### New member
would use angle formula α = 2 * arcsin( r / s ) where s is the slope s = √(h² + r²) ... r is radius

#### Dr.Peterson

##### Elite Member
The fourth part of the question (d), I can't find the value for the angle. Tried everything.

View attachment 20725View attachment 20726
I doubt that you've literally tried everything; it would be helpful to see some specifics.

I'd find the radius and arc length of the sector, and use those. The arc length is the entire circumference of the cylinder.