Assuming the validity of the statement that the internal bisectors of the angles of a triangle are concurrent, prove that the altitudes of a triangle are concurrent.

If the measures of the medians of a triangle are equal then prove that the triangle is equilateral.

If the areas of a similar triangle are equal,prove that they are congruent.

Prove that the bisectors of the opposite angles of a parallelogram are parallel.

Choose the correct one If angles of a triangle are in A.P. then one of the angle is

If cosines of two angles of a triangle are proportional to the opposite sides, show that the triangle is isosceles

The sides of a triangle measure 13 cm,12 cm,and 5 cm.prove that the triangle is right angled.

The angles of a triangle are in the ratio 1:3:5. Find them in radian

If the altitude of two similar triangle are in the ratio 2:3 what is the ratio of their areas?

the altitude AM and BN of a triangle ABC intersects at P. prove that triangleAPN and triangleBPM are similar.

Prove that the ratio of the areas of two similar triangles is equal to the ratio of the squares of the bisectors of the corresponding angles of the triangles. [The end-points of the angular bisectors are on the opposite sides of the angles.]