[求助] GWD29-31

[misia]

Q31

Phobus, one of the satellites of Mars, revolves about Mars at a distance of approximately 5,800 miles from the center of Mars and approximately 3,700 miles from the surface of Mars. If it is assumed that Mars is spherical and the orbit of Phobus is circular, what is the approximate circumference, in miles, of Mars at its equator?

A. 2,100π (π=拍. 不好意思打不出來這個符號)
B. 4,200π
C. 7,400π
D. 9,500π
E. 190,000π

答案是B

這題該怎麼算呢 ?
謝謝~~

[Ricky1120]

5800-3700=2100--->radius of Mars
2100*2=4200--->diameter
so 4200拍 就是答案了

[misia]

非常謝謝!!
原來這麼簡單
看來是沒讀懂題意....