Question

Your cake recipe is for a 9-inch-by-13-inch rectangular pan. You have a round pan you can use if it has the same area as the rectangular pan. What should be the diameter of the round pan? Use 3.14 to approximate pi. Round your answer to the nearest tenth.

Answer 1

Area of rectangle = Length*Width
Area of rectangle = 13*9
Area of rectangle = 117

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The area of a circle formula is
A = pi*r^2
where A is the area of the circle and r is the radius

If the area of the rectangle is equal to the area of the circle, then we can replace the "A" with 117 and solve for r. We'll use 3.14 in place of "pi"

A = pi*r^2
117 = pi*r^2
117 = 3.14*r^2
3.14*r^2 = 117
r^2 = 117/3.14
r^2 = 37.2611464968152
r = sqrt(37.2611464968152)
r = 6.1041908961643

Double this radius to get the diameter
d = 2*r
d = 2*6.1041908961643
d = 12.2083817923286
d = 12.2

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Answer: the diameter of the round pan should be approximately 12.2 inches

Answer 2

Answer:

12.2

Step-by-step explanation:

117 in.2 ÷ 3.14 ≈ 37.3 in.2 The square root of 37.3, about 6.1 inches, is the radius. The diameter of the cake pan must be twice this radius, or about 12.2 inches.