please answer for the 7th,8th,9th and 10th

Dear Student, 

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 8. We have, $\frac{\angle A}{\angle B}=\frac{2}{7}$
    Now, we know that sum of adjacent angles of parallelogram is $180°$.
 So, 
       $$\begin{gathered} Let \angle A be 2x and \angle B be 7x. \\ So, 2x+7x=180° \\ 9x=180° \\ x=\frac{180°}{9} \\ x=20° \\ So, \angle A=20°\times 2=40° \\ and \angle B=20°\times 7=140° \\ Now, we know that the opposite angles of the paralle\log ram are equal. \\ So, \angle A=\angle C=40° \\ and \angle B=\angle D=140° \end{gathered}$$

Hope this information clears your doubts.

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