A triangle has vertices A, B, and C. Vertex A has an angle of pi/6 , vertex B has an angle of (pi)/12 , and the triangle's area is 24 . What is the area of the triangle's incircle?

1 Answer
Jul 3, 2017

The area of triangle's incircle is 6.45 sq.unit.

Explanation:

/_A = pi/6= 180/6=30^0 , /_B = pi/12=180/12= 15^0 , /_C= 180-(30+15)=135^0 , A_t=24
We now Area , A_t= 1/2*b*c*sinA or b*c=(2*24)/sin30 = 96 , similarly ,a*c=(2*24)/sin15 = 185.46 , and a*b=(2*24)/sin135 = 67.88

(a*b)*(b*c)*(c.a)=(abc)^2= (96*185.46*67.88) or
abc=sqrt((96*185.46*67.88)) = 1099.35

a= (abc)/(bc)=1099.35/96~~11.45
b= (abc)/(ac)=1099.35/185.46~~5.93
c= (abc)/(ab)=1099.35/67.88~~16.19

Semi perimeter : S/2=(11.45+5.93+16.20)/2=16.79
Incircle radius is r_i= A_t/(S/2) = 24/16.79=1.43
Incircla Area = A_i= pi* r_i^2= pi*1.43^2 =6.45 sq.unit.

The area of triangle's incircle is 6.45 sq.unit. [Ans]