Find the area of triangle two sides of which are 18 cm and 10 cm and the perimeter is 42 cm.

Find the area of a triangle, two sides of which are 8 cm and 11 cm and the perimeter is 32 cm (see Fig. 12.6).

Find the area of a triangle whose sides are 9 cm, 12 cm and 15 cm.

Find the area of a triangle whose sides are 3 cm, 4 cm and 5 cm.

Find the area of the triangle whose sides are 12 cm, 14 cm and 20 cm.

Find the area of a triangle whose sides are 18 cm 24 cm, and 30 cm in length. Find the height corresponding to the greatest side.

Find the areas of the squares whose sides are: 10 cm