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?

Answer: Option A

Solution

Answer: Option A

Solution:

$$\begin{array}{rl}& AC=\sqrt{{21}^2+{20}^2}\\ & =\sqrt{441+400}\\ & =\sqrt{841}\\ & =29\\ & R=\frac{AC}{2}=\frac{29}{2}=14.5\text{ cm}\end{array}$$