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Theorem 8.4 - Class 9th - In a parallelogram, opposite angles are equal. - Opposite angles of parallelogram


  1. Chapter 8 Class 9 Quadrilaterals
  2. Serial order wise
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Theorem 8.4: In a parallelogram, opposite angles are equal Given: A parallelogram ABCD with AC as its diagonal To prove: ∠ A = ∠ C & ∠ B = ∠ D Proof: Opposite sides of parallelogram is parallel So, AB ∥ DC and AD‖∥ BC Adding (1) and (2) ∠BAC + ∠DAC = ∠DCA + ∠ BCA ∠BAD = ∠DCB Similarly, we can prove ∠ADC = ∠ABC Hence Proved.

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.