Its a lot easier to do 1.200 - .200. Than to do 1.248- .239. How I see it, estimating always gives you something to fall back on or to help see if your exact answer is accurate
Answer:

Its a right angle triangle so trigonometry is used.
a is the hypotenuse, b is the adjacent.
Use sin to find a. Use tan to find b.
Use math-way or photo-math
Answer:
everything is in the picture