Question



1) ΔPQR is an equilateral triangle. Find m(arcQPR)

​

Answer 1

equilateral ΔPQR has been inscribed.

To find out- ∠QOR=?

Solution- The points P, Q &  R are on the circumference of the  circle since ΔPQR has been inscribed in the circle. Now the chord QR subtends ∠QOR to the centre O and ∠QPR to the circumference at P.

∴ By rule, ∠QOR=2∠QPR.........(i).

Now PQR is an equilateral Δ. Each of its angle is 60o. i.e ∠QPR=60o.

So, from (i), ∠QOR=2∠QPR=2×60o=120o.

Ans- Option B.