ABCD is a rhombus in which ∠BAC = 50°, then 3∠D – 2∠DAC is equal to :ABCD एक समचतुर्भुज है, जिसमें ∠BAC = 50° है, तब 3∠D – 2∠DAC बराबर है :

1. A120°
2. B140°
3. C150°
4. D160°

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Correct answer: B. 140°

Explanation

The diagonal AC of a rhombus bisects angle A, so ∠A = 2 × 50° = 100° and ∠DAC = 50°. Adjacent angles are supplementary, so ∠D = 180° − 100° = 80°. Then 3∠D − 2∠DAC = 240° − 100° = 140°.समचतुर्भुज का विकर्ण AC कोण A को समद्विभाजित करता है, अतः ∠A = 2 × 50° = 100° और ∠DAC = 50°। आसन्न कोण संपूरक होते हैं, इसलिए ∠D = 180° − 100° = 80°। तब 3∠D − 2∠DAC = 240° − 100° = 140°।