SOLUTION: Find the angle at the centre of the sector, When the perimeter is 64 cm and radius is 21cm.

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Question 1003581: Find the angle at the centre of the sector,
When the perimeter is 64 cm and radius is 21cm.
Answer by josgarithmetic(39631) About Me  (Show Source):
You can put this solution on YOUR website!
The arc is some length alpha.
radius, given as 21; full circumference is 2%2Api%2A21=42pi.

Perimeter of sector is given as 64;
2%2A21%2Balpha=64
alpha=64-2%2A21
alpha=22, centimeter length units.

A full circle central angle measure would be 2pi.
The example central angle is a fraction of 2pi.

Central Angle Measure in radians, %2822%2F42pi%29%2A2pi,
highlight%2822%2F21%29 RADIANS

As degrees,