DEF is the triangle formed by joining the points of contact of the incircle with the sides of the triangle ABC : prove that
its angles are `(pi)/(2) - (A)/(2), (pi)/(2) - (B)/(2)" and " (pi)/(2) - (C )/(2)`.

DEF is the triangle formed by joining the points of contact of the incircle with the sides of the triangle ABC : prove that its sides are 2r cos (A)/(2), 2r cos (B)/(2)," and " 2r cos (C )/(2) .

DEF is the triangle formed by joining the points of contact of the incircle with the sides of the triangle ABC : prove that its area is (2triangle^2)/(abcs), i.e. (1)/(2) (r )/(R )triangle .

D E F is the triangle formed by joining the points of contact of the incircle with the sides of the triangle A B C ,\ prove that its sides are 2rcosA/2,\ 2rcosB/2\ a n d\ 2rcosC/2 where r is the radius of incircle of A B Cdot its angles are pi/2-A/2,pi/2-B/2a n dpi/2-C/2 its area is (r^2s)/(2R) where ' s ' is the semiperimter and R is the circumradius of the A B C .

In triangle ABC , prove that sin .(A)/(2)+ sin. (B)/(2) -sin. (C)/(2)=-1+4 cos.(pi-A)/(4)cos. (pi-B)/(4)sin. (pi-C)/(4)

If the sides of the triangle are p,q,sqrt(p^(2)+q^(2)+pq,) then the greatest angle is : a) (pi)/(2) b) (5pi)/(4) c) (2pi)/(3) d) (7pi )/(4)

In triangle ABC, prove that cos .(A)/(2)+cos.(B)/(2)+cos. (C)/(2) =4 cos .(pi-A)/(4)cos. (pi-B)/(4) cos.(pi-C)/(4)

In any triangle ABC,sin A-cos B=cos C, the angle B is a.(pi)/(2) b.(pi)/(3) c.(pi)/(4) d.(pi)/(6)

IF the lengths of the side of triangle are 3,5A N D7, then the largest angle of the triangle is pi/2 (b) (5pi)/6 (c) (2pi)/3 (d) (3pi)/4

IF the lengths of the side of triangle are 3,5A N D7, then the largest angle of the triangle is pi/2 (b) (5pi)/6 (c) (2pi)/3 (d) (3pi)/4

In Delta ABC , prove that cos. (A)/(2)+cos. (B)/(2) - cos .(C)/(2)=4cos .(pi+A)/(4) cos. (pi+B)/(4) cos. (pi-C)/(4)