Question

$PQ$ is the diameter of a semicircle with radius $4cm$ and $\angle PRQ$ is the angle on the semicircle. If $QR=2\sqrt{7}cm$, then length of $PR$ is :

• A. $8cm$
• B. $6cm$
• C. $5cm$
• D. $2\sqrt{11}cm$

Answer 1

The correct option is B $6cm$

$\angle PRQ={90}^{\circ }\Rightarrow PR=\sqrt{(PQ{)}^2-(RQ{)}^2}$

$=\sqrt{64-28}$

$=6$.

$\therefore$ The solution is $6$