Question

If tan a is equal to root 3minus 1 by root 3plus 1 then cos A is equal to

Answer 1

Answer:(√3+1)/2√2

Step-by-step explanation:

tanA=(√3-1)/(√3+1)

tanA=(√3-1)/(1+√3×1)

tanA=(tan60°-tan45°)/(1+tan60°×tan45°)

tanA=tan(60°-45°)

tanA=tan15°

=> A=15°

So, cosA=cos15°=(√3+1)/2√2