The answer to the question
B. 47 degrees
Explanation:
They already cut 43 degrees and they want to cut until a right angle is form which is 90 degrees. To find how much more they have to cut, do 90-43 which gives you 47.
Notice that when

, you have

so

is a solution, and the cubic has

as a factor. This means you can divide to get another quadratic factor and thus two more solutions.

So,

You can use the quadratic formula here: