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Geometry and Trigonometry Difficulty: Medium

Circle K has a radius of 4 millimeters mm. Circle L has an area of 100π mm2. What is the total area, in mm2, of circles K and L ?

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Explanation

Choice D is correct. The area, A , of a circle is given by the formula A=πr2, where r represents the radius of the circle. It’s given that circle K has a radius of 4 millimeters mm. Substituting 4 for r in the formula A=πr2 yields A=π42, or A=16π. Therefore, the area of circle K is 16π mm2. It’s given that circle L has an area of 100π mm2. Therefore, the total area, in mm2, of circles K and L is 16π+100π, or 116π.

Choice A is incorrect. This is the sum of the radii, in mm, of circles K and L multiplied by π, not the total area, in mm2, of the circles.

Choice B is incorrect. This is the sum of the diameters, in mm, of circles K and L multiplied by π, not the total area, in mm2, of the circles.

Choice C is incorrect and may result from conceptual or calculation errors.