Hello from MrBillDoesMath!
Answer:
Choice "a"
Discussion:
See attachment for definition of sides
Perimeter = a + b + c
where a,b are sides and c is the hypotenuse. So
Perimeter =
7 (1/2) + 7 ( sqrt(3)/2) + 7 =
7 ( 1/2 + sqrt(3)/2 + 1) = => as 1/2 + 1 = 3/2
7( 3/2 + sqrt(3)/2) ) = => factor (1/2) form each term
(7/2) ( 3 + sqrt(3))
which is Choice "a".
Thank you,
MrB