Rules for a 30-60-90 right triangle:
hyp = 2 * short leg
Long leg = sqrt(3) * short leg
Given:
hyp = 7
7 = 2*short leg
divide both sides by 2
7/2 = short leg
long leg = sqrt(3) * short leg
long leg = sqrt(3) * (7/2)
long leg = 6.06
P= s1 + s2 + s3
P = 7 + 3.5 + 6.06
P = 16.56 units (Decimal approximation)
P = 10.5 + 3.5sqrt(3) units (Exact value)
