Consider both Earth and Mars to be spheres. The surface area of mars is about 28% that of earth. What is the ratio of their radii?

Question

asnaseer · Answer

do you know the formula for the surface area of a sphere?

anonymous · Answer

4pir^2

asnaseer · Answer

correct, so lets call the radius of Mars $r_m$ and the radius of Earth $r_e$

anonymous · Answer

ok

asnaseer · Answer

you are given:$$\frac{4\pi r_m^2}{4\pi r_e^2}=\frac{28}{100}$$

asnaseer · Answer

and you need to work out what $\displaystyle\frac{r_m}{r_e}$ is from this.

asnaseer · Answer

can you do it now?

anonymous · Answer

if 4pir^2 is the area of a sphere then the surface area of mars compared to that of earth is 0.28*(4pir^2) if earth's is just 4pir^2 right. equate both sides and solve for r. Asnaseer's answer might be more thorough but if you know how to solve for r here with basic algebra that's all there is to it.

anonymous · Answer

yeah I forgot how you solve for r

anonymous · Answer

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