A triangle has two corners with angles of pi / 12 π12 and pi / 8 π8. If one side of the triangle has a length of 1 1, what is the largest possible area of the triangle?

1 Answer
Dec 2, 2017

Largest possible area of the triangle = color(blue)(0.45)=0.45

Explanation:

Sum of the three angles of a triangle is equal to 180^0 or pi^c1800orπc

/_A = (pi)/12, /_B = pi/8,A=π12,B=π8,
/_C = pi -(( pi/12) + (pi/8)) =pi - (5pi)/24 = (19pi)/24C=π((π12)+(π8))=π5π24=19π24

To get the largest possible area, length 1 should correspond to the smallest /_A = pi/12A=π12

a / sin( /_A )= b / sin( /_B )= c / sin( /_C)asin(A)=bsin(B)=csin(C)

1 / sin (pi/12) = b / sin (pi/8) = c / sin ((19pi)/24)1sin(π12)=bsin(π8)=csin(19π24)

b = (1 * sin ((pi)/8)) / sin (pi /12)b=1sin(π8)sin(π12)
b = 0.3827 / 0.2588 =color(blue)( 1.4787)b=0.38270.2588=1.4787

c = (1*sin (19pi/24))/ sin (pi/12)c=1sin(19π24)sin(π12)
b = 0.6088 / 0.2588 = color(blue)( 2.3524)b=0.60880.2588=2.3524

Semi-Perimeter s = (a + b + c )/2 =( 1 + 1.4787 + 2.3524 )/2= color (green)(2.4156)s=a+b+c2=1+1.4787+2.35242=2.4156

s - a = 2.4156 - 1 = 1.4156sa=2.41561=1.4156
s - b = 2.4156 - 1.4787 = 0.9369sb=2.41561.4787=0.9369
s - c = 2.4156 - 2.3524 = 0.0632sc=2.41562.3524=0.0632

Area of Delta ABC = sqrt(s (s-a) (s - b) (s - c))
= sqrt ( 2.4156 * 1.4156 * 0.9369 * 0.0632) = 0.45