The diameters of two semi-circles are 40 cm and 46 respectively. Find their total area.

Question

anonymous · Answer

well remember the area of a circle formula is just:

$$A = \pi r^2 $$

and remember that radius is just half the diameter, since we have the diameter, we can plug it in to find the radius

r = 1/2D

r = 1/2 (40) = 20
$$A = \pi (20)^2 $$$$= \pi 400$$

using this same method we can find the other circle:

r = 1/2D

r = 1/2 (46) = 23

$$A = \pi (23)^2 $$
$$= \pi529 $$

anonymous · Answer

so how do i get the total area?

anonymous · Answer

oh wait its a semi circle, we have to halve the our results:

$$A_{1}= 1/2(\pi400) = \pi 200$$

$$A _{2}= 1/2(\pi529) = \pi264.5$$

anonymous · Answer

I'm not sure what they mean by total area. Do they want the area of each semi-circle or the combined area?

if it is combined then add them together

anonymous · Answer

o alright thanks its combined area.