A triangle has two corners with angles of pi / 12 π12 and pi / 4 π4. If one side of the triangle has a length of 14 14, what is the largest possible area of the triangle?

1 Answer
Feb 28, 2018

Longest possible perimeter PerimeterPerimeter P = color(purple)(84.9374P=84.9374

Explanation:

Given hat A = pi / 12, hat B = pi / 4, hatC = pi - pi/12 - pi/4 = (2pi)/3ˆA=π12,ˆB=π4,ˆC=ππ12π4=2π3

To get the longest perimeter, side 14 should correspond to the least hatAˆA.

Applying law of sines,
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12 / sin (pi/12) = b / sin (pi/4) = c / sin ((2pi)/3)12sin(π12)=bsin(π4)=csin(2π3)

b = (12 * sin (pi/4)) / sin (pi/12) = 32.7846b=12sin(π4)sin(π12)=32.7846

c = (12 * sin ((2pi)/3)) / sin (pi/12) = 40.1528c=12sin(2π3)sin(π12)=40.1528

Perimeter P = 12 + 32.7846 + 40.1528 = color(purple)(84.9374P=12+32.7846+40.1528=84.9374