MHB Looking Answer About Area of Circle.

[susanto3311]

hello all...

i'am looking for a formula to solve this multiple choice question about area of circle...

like my picture below ...

any body can help me, thanks in advance...

susanto3311

 

[SuperSonic4]

hello all...

i'am looking for a formula to solve this multiple choice question about area of circle...

like my picture below ...

any body can help me, thanks in advance...

susanto3311

The area of the bit of the circle left will be area of the whole circle less the area of the cut out sector. The formulae for the area of a sector (in degrees) is given by

$$A_s = \dfrac{\theta}{360} \pi r^2$$

In this case $$\theta$$ is the angle of the sector (i.e. the missing piece in your example)

 

[susanto3311]

The area of the bit of the circle left will be area of the whole circle less the area of the cut out sector. The formulae for the area of a sector (in degrees) is given by

$$A_s = \dfrac{\theta}{360} \pi r^2$$

In this case $$\theta$$ is the angle of the sector (i.e. the missing piece in your example)

the answer is 462...do you agree?

 

[SuperSonic4]

the answer is 462...do you agree?

I get B as my answer (although the question could stand to be clearer about whether or not it wants the area of the cut out sector or the area of "pacman" - the bit that's left).

How did you arrive at 462 (which is the area of the sector)? Don't forget that's just the area of the sector - you need to subtract this from the area of the whole

 

[susanto3311]

I get B as my answer (although the question could stand to be clearer about whether or not it wants the area of the cut out sector or the area of "pacman" - the bit that's left).

How did you arrive at 462 (which is the area of the sector)? Don't forget that's just the area of the sector - you need to subtract this from the area of the whole

hi super...

thanks. i'am missing you are right...