m(<A ) = a
m(<B) = b
m(<C) = c
{a,b,c} i.p { 0,(3);0,25;0,2}
a+b+c= 180°
a* 0,(3)= b*0,25= c*0,2 = k
a= k*0,(3) = K :3/9 = k/1 *9/3 = k/1 = 3/1 = 3 k
b= k*025= k:25/10 = k*10/25 = k/1 * 25/100 = k/1* 4/1 = 4k
c = k*0,2= k:2/10 = k/1*10/2 = k/1 *5/1 = 5 k
3k +4k +5k = 180°
12k = 180°
k= 180° :12
k= 15
a= 3*15 = 45
b= 4*15 = 60
c= 5*15 = 75