The lengths of the two sides forming the right angle of a right-angled triangle are 21 cm and 20 cm. What is the radius of the circle circumscribing the triangle?

14.5 cm

We know that,

Hypotenuse² = Base² + Perpendicular²

Circum-radius of the right-angled triangle = Hypotenuse/2

We have,

Base = 21 cm

Perpendicular = 20 cm

According to the question,

= (Hypotenuse)² = 21² + 20²

= 441 + 400

= 841

= (Hypotenuse) = √841 = 29

Circum-radius of the right-angled triangle = 29/2 = 14.5 cm