Mathematics: In parallelogram a b c d, measure of angle a d c equals 60 degrees. what is measure of angle d c b?

In parallelogram a b c d, measure of angle a d

19thomasar

09.10.2021

Length of rectangle is 1 unit

Solution:

Given that

Length of a rectangle is width minus 8 units.

Area of rectangle = 9 square units

Need to calculate the length of rectangle.

Let us assume width of rectangle = x

As Length is width minus 8,

Length of the rectangle = x – 8

$\text{ Area of rectangle }=\text{ width of rectangle }\times \text{ Length of the rectangle }$

$\text{ Area of rectangle }= x\times (x-8)$

$\text { Area of rectangle }=\left(x^{2}-8 x\right)$

As given that area of rectangle = 9 square units

$\begin{array}{l}{\Rightarrow x^{2}-8 x=9} \\\\ {\Rightarrow x^{2}-8 x-9=0}\end{array}$

On solving above quadratic equation for x, we get

$\begin{array}{l}{\Rightarrow x^{2}-9 x+x-9=0} \\\\ {\Rightarrow x(x-9)+1(x-9)=0} \\\\ {\Rightarrow (x-9)(x+1)=0}\end{array}$

When x-9 =9, x = 9

When x + 1 = 0, x = -1

As width cannot be negative, so considering x = 9

$\text{ Length of rectangle }= x-8 = 9-8 = 1 \text{ unit }$

Hence, Length of rectangle is 1 unit.

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