# Question #e4968

##### 1 Answer

Apr 3, 2016

The line AH is tangential to the earth's surface, hence angle AHO will be

Angle HAO will be

We know that:

- line OH has length

- line OA has length

We can now use the cosine rule in relation to angle HOA

rearranging to find

Using the above in a calculator gives r=6,373km