Multiple choice

Angle subtended by a chord PQ on the circumference is 90 degree. If radius of this circle is 15 cm, then what is the length of PQ ?

  1. 35 cm

  2. 40 cm

  3. 7.5 cm

  4. 30 cm

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If an angle subtended by a chord on the circumference is 90°, then that chord is the diameter of the circle (Thales' theorem). The chord PQ is therefore the diameter. Given radius = 15 cm, diameter = 2 × 15 = 30 cm. So length of PQ = 30 cm. Options A, B are incorrect calculations, and option C is just the radius length.