Anonymous
Anonymous asked in Science & MathematicsMathematics · 2 months ago

please help with this circle theorem question?

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  • 2 months ago
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    Observed that ABCD is a cyclic quadrilateral. In a cyclic quadrilateral, the sum of opposite angles is 180 degrees. A radius is perpendicular to a tangent. So angle DCO = 90 - 32 = 58 degrees

    Since OB is parallel to the tangent line, triangle BCO is an isosceles right triangle with OB = OC = radius. So angle OCB = angle OBC = 45 degrees.  Then angle DCB = angle DCO + angle OCB = 58 + 45 = 103 deg

    So

    angle DAB + angle DCB = 180

    angle DAB + 103 = 180

    angle DAB = 77 degrees

    You can award me the best answer if you want my solution.

    • JOHN
      Lv 7
      2 months agoReport

      Your answer is correct and deserves the BA.

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