Prove that of all triangles on the same base and of the same area, the isosceles triangle has the least perimeter.

Prove that of all the triangles with a given base and a given vertex angle, an isosceles triangle has the greatest bisector of the vertex angle.

Prove that two triangles on the same base and between the same parallels are equal in area.

Prove that , of all rectangles of given area , the square has the least perimeter.

Prove that among all the rectangles of the given area, square has the least perimeter.

If a triangle and a parallelogram are on the same base and between the same parallels, then prove that the area of the triangle is equal to half the area of the parallelogram.

If a triangle and a parallelogram are on the same base and between the same parallels, then prove that the area of the triangle is equal to half the area of the parallelogram.

If a triangle and a parallelogram are on the same base and between the same parallels, then prove that the area of the triangle is equal to half the area of the parallelogram.

If a triangle and a parallelogram lie on the same base and between the same parallels, then prove that the area of the triangle is equal to half of the area of parallelogram.

Find the area of an isosceles triangle with perimeter 36 cm and base 16 cm.