Details? you need to add the whole question
Answer is C! Hope it helps
I believe the 3rd answer down if the information you provided is correct
Squaring the sum on the top, rules out 1 and 2 (not squaring the 7 only)
then 4 times the difference. so I believe 4 (x-1) on the bottom.
I highly recommend using the unit circle; the answer is 1/2.
