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3 years ago

#22-11: Determine the difference in area between circle A and circle B. Use 3.14 for pi.

Mathematics

1 answer:

topjm [15]3 years ago

5 0

Answer:

7.065

Step-by-step explanation:

There are two ways to do this:

(Note: area = pi * r^2)

Method 1:

Diameter of A = 4, so radius = 4/2 = 2

Area of A = 3.14 * 2^2 = 12.56

Diameter of B = 5, so radius = 5/2 = 2.5

Area of B = 3.14 * 2.5^2 = 19.625

Difference in area = 19.625 - 12.56 = 7.065

Method 2:

First find out how much larger the diameter of B is than A, so 5/4 = 1.25.

What this means is if you take the diameter of A and multiply it by 1.25, you get the diameter of B.

When dealing with area, the area of B will be 1.25^2 times bigger than A.

Area of A = 3.14 * 2^2 = 12.56

So area B = 12.56 * 1.25^2 = 19.625

Difference = 19.625 - 12.56 = 7.065

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Find the value of k so that 48x-ky=11 and (k+2)x+16y=-19 are perpendicular lines.

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Answer: k = -1 +/- √769

Step-by-step explanation:

48x - ky = 11

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*************************************************************************

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$\frac{48}{k}$ and $-\frac{(k + 2)}{16}$ are perpendicular so they have opposite signs and are reciprocals of each other. When multiplied by its reciprocal, their product equals -1.

$-\frac{(k + 2)}{16}$ * $\frac{k}{48}$ = -1

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Cross multiply, then solve for the variable.

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