Question

the value of 7cos^2A+7sin^2A-3 is
​

Answer 1

7 sin²A + 3 cos²A = 4

=> 3 sin²A + 3 cos²A + 4 sin²A = 4

=> 3 ( sin²A + cos²A ) + 4 sin²A = 4

=> 3 + 4 sin²A = 4

=> 4 sin²A = 1

=> sin²A = 1/4

=> sin A = 1/2

=> sin A = sin 30°

=> A = 30° .  

So , tan A = tan 30° = 1/√3  

Answer 2

7 cos2a + 7sin2a - 3

= 7(cos2a + sin2a)-3

= 7*1 -3

=7-3

=4

hope it helps