Question:
In a parallelogram PQRS, if ∠P = 60o, then other three angles are
(a) 45o, 135o, 120o
(b) 60o, 120o, 120o
(c) 60o, 135o, 135o
(d) 45o, 135o, 135o
Solution:
(b) 60o, 120o, 120o
In parallelogram ∠P and ∠Q are supplementary.
We know that, sum of supplementary angle is equal to 180o.
Then, ∠P + ∠Q = 180o
∠60o + ∠Q = 180o
∠P = 180o – 60o
∠P = 120o
And also, opposite angles ∠P and ∠R are equal in parallelogram.
So, ∠P = ∠R = 60o
∠Q = ∠S = 120o
Therefore, the other three angles of parallelograms are 60o, 120o and 120o.