Two corners of a triangle have angles of (5 pi )/ 8 5π8 and ( pi ) / 12 π12. If one side of the triangle has a length of 7 7, what is the longest possible perimeter of the triangle?

1 Answer
May 3, 2018

color(brown)("Longest possible perimeter " P = 53.45 " sq units"Longest possible perimeter P=53.45 sq units

Explanation:

hat A = (5pi)/8, hat B = pi/12, hat C = pi - (5pi)/8 - pi/12 = (7pi)/24ˆA=5π8,ˆB=π12,ˆC=π5π8π12=7π24

color(blue)("As per Law of Sines,' color(crimson)(a / sin A = b / sin B = c / sin C

To get the longest perimeter, side of length 7 should correspond to least angle hat B = pi/12

:. a / sin ((5pi)/8) = 7 / sin (pi/12) = c / sin ((7pi)/24)

a = (7 * sin ((5pi)/8)) / sin (pi/12) ~~ 24.99

c = (7 sin ((7pi)/24)) / sin (pi/12) ~~ 21.46

color(brown)("Longest possible perimeter " P = 7 + 24.99 + 21.46 = 53.45