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COMEDK2019MathematicsProperties of Triangles

T. The angles A, B and C of a A B C are in A.P. If b: c= 3 : 2 , then the angle A is

Options

  1. A30^
  2. B15^
  3. C75^
  4. D45^

Correct answer

C. 75^

Step-by-step solution

It is given that A, B, C are in AP . Now, A+B+C=180^ B+2 B=180^ B=60^ Now, using sine rule, we have b B = c C C= c b B= 2 3 60^ [ b: c= 3 : 2 ]= 2 3 3 2 = 1 2 c=45^ Now, A+B+C=180^ A+60^ +45^ =180^ A=75^

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