Question

A central angle of a circle measures 1.5 radians. If the radius of the circle is 3 cm, what is the area of the related sector?

Answer 1

Answer:

Option B. $6.75\ cm^{2}$

Step-by-step explanation:

we know that

The area of a circle is equal to

$A=\pi r^{2}$

we have

$r=3\ cm$

substitute

$A=\pi (3^{2})=9 \pi\ cm^{2}$

Remember that

$2\pi$ radians subtends the complete circle of area $9 \pi\ cm^{2}$

so

by proportion

Find the area of the related sector for a central angle of $1.5$ radians

Let

x------> the area of the related sector

$\frac{9 \pi}{2\pi}\frac{cm^{2}}{radians} =\frac{x}{1.5}\frac{cm^{2}}{radians}\\ \\x=9*1.5/2\\ \\x= 6.75\ cm^{2}$