One leg of a right-angled triangle is 30 mm, and the second leg is 100 mm. Find the area of this rectangle

Let triangle ABC be right-angled and angle B a straight line.

Then AB and BC are legs.

By the condition of the problem AB = 30 mm and BC = 100 mm.

The area of a right-angled triangle is equal to half the product of the legs:

S = 1/2 * AB * BC = 1/2 * 30 * 100 = 1500.

Answer: the area of the triangle is 1500 sq. Mm.