First of all be more spusific in your question
I believe he should add 2ft to the height of the tree as well
The law of cosines states that:
c^2=a^2+b^2-2abcosC
You already have all the values for the variables with the exception of x so:
x^2=25+100-100cos60
x=√(125-100cos60)
x=√75
x≈8.66 to nearest one-hundredth...
