Q13 of 35 Page 3


In a parallelogram, one angle is 4/5 thof the adjacentangle. Determine the angles of the parallelogram.


Let x° and y° be the two adjacent angles of the parallelogram (x>y).
According to the given condition,
y = (4/5) x … (1)
But x+y =180 … (2)
Putting y = (4/5)x in (2) we get x + (4/5) x = 180
or (9/5)x = 180, ⇒ x = 180 × (5/9) = 100
y = (4/5)(100) = 80
The opposite angles of a parallelogram are equal.
∴ The angles of the parallelogram are 100°, 80°, 100° and 80°.

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