First of all youre not going to get a direct answer to all of these questions, youre going to have 3 finally equations(because thats the amount of variables you have).
Step 1
<u>Find the value of TS</u>
we know that
if PQ is parallel to RS. then triangles TRS and TPQ are similar
so

solve for TS

we have


substitute

Step 2
<u>Find the value of SQ</u>
we know that

we have


substitute

therefore
<u>the answer is</u>
the value of SQ is 
Answer: Earth: radius = 6378 kilometer, diameter = 12756 kilometers.