Find the area of a right-angled triangle whose legs are AB 30mm BC 4cm.

We are given a right-angled triangle ABC, in which leg AB is 30 millimeters, and leg BC is 4 centimeters, we need to find the area of this right triangle in millimeters.

To begin with, let’s translate the BC side into millimeters, we get: 4 * 10 = 40 (millimeters);

Now we can find the area of the given triangle. The area of a right-angled triangle is half the product of its legs, therefore:

S (ABC) = 10 * 40/2 = 200 (mm²)

Answer: the area of this right-angled triangle is 200 mm².