Question

*PLEASE ANSWER* What is the area of minor sector AOB?

Answer 1

Answer: Approximately 13 square units (choice B)

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Explanation:

The given reflex angle is 215 degrees. A reflex angle is anything over 180 degrees, but less than 360. Subtract 215 from 360 to get the measure of angle AOB

angle AOB = 360 - 215 = 145

angle AOB = 145 degrees

We'll use this later.

Now find the area of the full circle. Use the formula A = pi*r^2. The radius is r = sqrt(10) which can be found through the distance formula or the pythagorean theorem. You want to find the length of either OA or OB to get the radius.

The area of the circle is

A = pi*r^2

A = pi*(sqrt(10))^2

A = 10pi

This is the exact area of the full circle, but we want just a fractional portion of it. Specifically we want the pie slice that is formed by angle AOB

area of sector AOB = [ (angle AOB)/360 ] * (area of full circle)

area of sector AOB = (145/360)*10pi

area of sector AOB = 145pi/36

area of sector AOB = 145*3.14/36

area of sector AOB = 12.647 approximately

area of sector AOB = 13 square units approximately, after rounding to the nearest whole number