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AP EAMCET2003MathematicsProperties of Triangles

In a triangle, if b=20, c=21 and A= 3 5 , then a is equal to :

Options

  1. A12
  2. B13
  3. C14
  4. D15

Correct answer

B. 13

Step-by-step solution

We have, b=20, c=21 and A= 3 5 Now, ^2 A=1- ^2 A=1- ( 3 5 )^2=1- 9 25 = 16 25 A= 4 5 Now, A= b^2+c^2-a^2 2 b c 4 5 = (20)^2+(21)^2-a^2 2 20 21 400+441-a^2=672 a^2=841-672=169 a=13

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