b) The value of the side CD is 25 unit.
What is quadrilateral ?
A quadrilateral is a two-dimensional closed figure which has four sides, four vertices and four angles.
Quadrilateral has many types, which are,
Parallelogram, Rectangle, Square, Rhombus, Trapezium, Kite.
What is the value of required side ?
Given that,
AB = 4x+21, BC = 6x+15, CD = 8x+1
According to the diagram, Two adjacent sides AB and BC are equal.
∴ AB = BC
⇒ 4x+21 = 6x+15
⇒ 6x-4x = 21-15
⇒ 2x = 6
⇒ x = 3
Now, CD = 8x+1 = 8×3+1 = 25
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