In parallelogram ABCD ∠A =3 times ∠B find all the angles of the parallelogram in the same parallelogram if AB = 5x- 7 and CD = 3x+ 1 find the length of CD
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In parallelogram ABCD, ∠A = 3 times ∠B.
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asked May 28, 2019 in Class VIII Maths by muskan15 (-3,443 points)
In parallelogram ABCD, ∠A = 3 times ∠B. Find all the angles of the parallelogram. In the same parallelogram, if AB = 5x – 7 and CD = 3x +1 ; find the length of CD.
special types of quadrilaterals
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answered May 28, 2019 by navnit40 (-4,939 points)

Let ∠B = x
∠A = 3 ∠B = 3x
AD || BC
∠A + ∠B = 180°
3x + x = 180°
⇒ 4x = 180°
⇒ x = 45°
∠B = 45°
∠A = 3x = 3 x 45 = 135°
and ∠B = ∠D = 45°
opposite angles of || gm are equal.
∠A = ∠C = 135°
opposite sides of //gm are equal.
AB = CD
5x – 7 = 3x + 1
⇒ 5x – 3x = 1+7
⇒ 2x = 8
⇒ x = 4
CD = 3 x 4+1 = 13
Hence 135°, 45°, 135° and 45° ; 13