Question

if cos A=3/5 A is acute find sinA

Answer 1

We know that:

cos²A + sin²A = 1

==> 3²/5² + sin²A = 1

==> sin²A = 1 - 9 / 25

==> sin²A = ( 25 - 9 ) / 25

==> sin²A = 16 / 25

==> sin A = 4/5

The value of sin A is 4/5

Hope it helps you.

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Answer 2

cosA = 3/5 so sinA=4/5