Question

The sum of two circles is 80 pi square meters. Find the length of the radius if one of them is twice as long as the other

Answer 1

Answer:

Length of Radius of large circle= 8

Lenght radius of first circle= 2

Step-by-step explanation:

THIS IS THE COMPLETE QUESTION

The sum of the areas of two circles is 80π square meters. Find the length of a radius of each circle if one of them is twice as long as the other.

What is the radius of the larger circle?

Area of a circle can be calculated by Below formula

A = πr^2............eqn(1)

Let ( X) = area of first circle

Y= the area of second circle

Rx= radius of first circle

Ry = radius of second circle

From the question, we know that

[X+ Y] = 80π .......eqn(2)

Substitute the radius formula for the area,

[π(Rx)^2 + π (Ry)^2] = 80π ......eqn(3)

But from the question, Radius of second circle is twice of the second one, then

Ry = 2Rx ..........eqn(4)

If we substitute eqn (4) into eqn(3)

[ π(Rx)^2 + π (2Rx)^2 = 80π

If factorize π out, then cancel it out

π[(Rx)^2 + π (2Rx)^2 = 80π

Then we have

(Rx)^2 + 4(Rx)^2 = 80

5(Rx)^2 = 80

(Rx)^2= 80/5

(Rx)^2= 16

(Rx)= 4

From eqn(4)

Ry = 2Rx

Ry= 2(4)

Ry= 8

Rx= 2 and Ry= 8

Hence, radius of first circle= 2

Lenght Radius of second circle= 8