Triangles

In a triangle ABC, if the sides are 13, 14, 15, the length of the altitude to the side 14 is:

A circle is inscribed in a triangle with sides 8, 15, 17. Its radius is:

The area of the circumcircle of an equilateral triangle with side 6 is:

In triangle ABC, side b = 20, c = 21 and sin A = 3/5. Find side a.

Two sides of a triangle are 4 and 10. Which cannot be the third side?

In triangle ABC, angle A = 30, B = 60. What is the ratio of sides a:b:c?

The coordinates of vertices of a triangle are (0,0), (6,0) and (0,8). The circumcenter is:

Find the area of a triangle with base 15 cm and altitude 10 cm.

A triangle with sides 6, 8, and 10 is similar to a triangle with sides:

If in triangle ABC, angle C is right angle, then cos^2 A + cos^2 B is:

The perimeter of an equilateral triangle is 18 cm. Its area is:

In triangle ABC, if AD is altitude and AE is circumradius, then area is:

Angle sum of a triangle is 180. This is based on which postulate?