169k views
5 votes
A sun's rays are vertical at the point A on a planet. At the point B, which is 2105 miles due north of A, the angle of the sun measured to be 7.4°. See the figure. Use this information to approximate the radius and circumference of the planet.

1 Answer

6 votes

Answer:

  • radius: 1460 mi
  • circumference: 9174 mi

Explanation:

If the angle of elevation at point B is 7.4°, then the sun is 90° -7.4° = 82.6° from the vertical. This is the measure of the central angle between the two points. That represents a fraction of a circle that is ...

82.6°/360° = 413/1800 ≈ 0.229444...(repeating)

The relation between the given distance and the circumference is ...

0.294444C = 2105 mi

C = 2105 mi/0.294444 ≈ 9174 mi

The radius of the spherical planet is this divided by 2π:

r = C/(2π) = 9174 mi/(2π) ≈ 1460 mi

The radius of the planet is about 1460 miles; the circumference is about 9174 miles.

User Anand C U
by
5.3k points