Ex.5.2 Q5 Lines and Angles - NCERT Maths Class 7

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Question

 In the given figure, the arms of two angles are parallel. If \(\angle ABC = 70^\circ,\) then find:

(i) \(\angle DGC\) (ii) \(\angle DEF\)

Text Solution

 

Reasoning:

Let’s visually model this problem. There is one operation that can be done. According to this model, the resultant value of corresponding angle will be equal to \(\angle DGC.\)

Now, it’s a matter of finding measure of \(\angle DGC.\)

Steps:

(i) Solve for \(\angle DGC\)

Given \(AB || DG\) and \(BC\) is transversal

Also\(, \angle ABC = 70^\circ\) (Given)

Since\(, \angle ABC = \angle DGC\) (Corresponding angles)

Therefore\(, \angle DGC = 70^\circ→(1)\)

Reasoning:

Let’s visually model this problem . There is one operation that can be done.According to this model, the resultant value of corresponding angle will be equal to \(\angle DGC.\) Now, it’s a matter of finding measure of \(\angle DEF.\)

Steps:

(ii) Solve for \(\angle DEF\)

Given \(BC || EF\) and \(DE\) is transversal

Also\(, \angle DGC = 70^\circ\) (from 1)

Since\(, \angle DGC = \angle DEF\) (Corresponding angles)

Therefore\(, \angle DEF = 70^\circ\)

  
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