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Then BDDC |
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Answer» AD^2 = BD × CD AD ÷ CD = BD ÷ AD ΔADC ∼ ΔBDA (by SAS ∠D = 90°) ∠BAD = ∠ACD ; ∠DAC = ∠DBA (Corresponding angles of similar triangles) ∠BAD+ ∠ACD + ∠DAC + ∠DBA = 180° ⇒ 2∠BAD + 2∠DAC = 180° ⇒ ∠BAD + ∠DAC = 90° ∴ ∠A = 90° |
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