Hushar Mulga
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▢MRPN is cyclic, ∠ R = (5x – 13)°, ∠ N = (4x + 4)°. Find measures of ∠ R and ∠ N.

Chapter 3 – Circle – Text Book Solution

Practice Set 3.4 | Q 3 | Page 73

▢MRPN is cyclic, ∠ R = (5x – 13)°, ∠ N = (4x + 4)°. Find measures of ∠ R and ∠ N.

solution

MRPN is a cyclic quadrilateral.
∴ ∠R + ∠N = 180º              (Opposite angles of a cyclic quadrilateral are supplementary)
⇒ 5x − 13º + 4x + 4º = 180º
⇒ 9x − 9º = 180º 
⇒ 9x = 180º + 9º = 189º
⇒ x = 21º
∴ ∠R = 5x − 13º = 5 × 21º − 13º = 105º − 13º = 92º
∠N = 4x + 4º = 4 × 21º + 4º = 84º + 4º = 88º
Thus, the measures of ∠R and ∠N are 92º and 88º, respectively.

Explanation:- 

Using the fact that opposite angles of a cyclic quadrilateral are supplementary, we have:

∠R + ∠N = 180°

Substituting the given values, we get:

5x – 13° + 4x + 4° = 180°

Combining like terms and simplifying, we get:

9x – 9° = 180°

Adding 9° to both sides, we get:

9x = 189°

Dividing by 9, we get:

x = 21°

Substituting this value for x, we can find the measures of angles R and N:

∠R = 5x – 13° = 5(21°) – 13° = 105° – 13° = 92°

∠N = 4x + 4° = 4(21°) + 4° = 84° + 4° = 88°

Therefore, the measures of angles R and N are 92° and 88°, respectively.

Chapter 3 – Circle – Text Book Solution

Practice set 3.4  | Q 3 | Page 73

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