Astudent on the ground observes the sun just as it sets. his friend, who is located 100 meters higher up in a tall building, tells him via cell phone that she observes the sun setting 77 seconds after he does. assuming that the path of the setting sun is perpendicular to the horizon, use this information to estimate the radius of the earth.

Rt≅6377Km

Explanation:

Take a look at the image. The horizontal line is the horizon, and the angle α corresponds to the earth rotation during the 77 seconds.

With this information, we can know the value of α:

α =

Since we have formed a rectangle triangle:

  Solving for Rt:

Rt≅6377467m=6377Km

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2