In a circle with a radius of 7 feet, the radian measure of the central angle subtended by an arc with a length of 4 feet is ? The area of the sector formed by the arc is ? square feet.

Assume π = 3.14, and round your answers to the nearest hundredth.

Respuesta :

Part 1)

we know that

The circumference of a circle is equal to

[tex]C=2\pi r[/tex]

where

r is the radius of the circle

In this problem we have

[tex]r=7\ ft[/tex]

substitute

[tex]C=2\pi 7=14\pi\ ft[/tex]

Remember that

[tex]2\pi[/tex] radians subtends the complete circle of length [tex]14\pi\ ft[/tex]

so

by proportion

Find the radian measure of the central angle subtended by an arc with a length of [tex]4[/tex] feet

[tex]\frac{2\pi}{14\pi} \frac{radians}{feet} =\frac{x}{4} \frac{radians}{feet} \\ \\14\pi*x=4*2\pi \\ \\x=8/14 \\ \\ x=0.57\ radians[/tex]

therefore

the answer Part 1) is

[tex]0.57\ radians[/tex]

Part 2)

we know that

The area of a circle is equal to

[tex]A=\pi r^{2}[/tex]

where

r is the radius of the circle

In this problem we have

[tex]r=7\ ft[/tex]

substitute

[tex]A=\pi 7^{2}=49\pi\ ft^{2}[/tex]

Remember that

The area of complete circle [tex]49\pi\ ft^{2}[/tex] subtends a length of the complete circle of  [tex]14\pi\ ft[/tex]

so

by proportion

Find the area of the sector formed by an arc with a length of [tex]4[/tex] feet

[tex]\frac{49\pi}{14\pi} \frac{ft^{2}}{ft} =\frac{x}{4} \frac{ft^{2}}{ft} \\ \\14*x=49*4 \\ \\x=14 \ ft^{2}[/tex]

therefore

the answer Part 2) is

[tex]14 \ ft^{2}[/tex]

The area of the sector formed by the arc is 14 sq. ft.

What is the circumference of a circle?

The circumference of a circle is equal to 2πr.

where

r is the radius of the circle.

In this problem we have

r = 7 ft

substitute

The circumference of a circle = 2πr = 14π

radians subtends the complete circle of length 14π ft.

In order to find the radian measure of the central angle subtended by an arc with 4 ft length.

2π/14π = x /4

x = 8/14

x = 0.57 radians

Part 2)

The area of a circle is equal to πr^2.

where

r is the radius of the circle

A = 49 π sq. ft

The area of the complete circle of 49 π sq. ft subtends the length of the complete circle of 14 π ft.

The area of the sector formed

49 π / 14 π = x/ 4

x = 14 sq. ft

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