$$ sin^2 5° + sin^2 10°+sin^2 15°+.....sin^2 85°+sin^2 90°$$ is equal to

$$ {Cos^4θ +Sin^4θ}={2 \over3} $$ then the value of $$ {Cos^2θ -Sin^2θ+1}$$?

If 0 ≤ θ ≤ 90⁰ and 4cos²θ - $$4{\sqrt { 3} \ }cosθ$$ + 3 = 0, then the value of θ is : 

If cos θ = $${1\over \sqrt{10}}$$, then tan θ is equal to.

If cos²α + cos²β = 2, then the value of tan³ α + sin⁵ β is :

If $$ {secθ+tanθ\over secθ - tanθ} $$= $$ 2{51\over 79} $$ sinθ then the value of sin θ is :

What is the value of

If $$ sin(θ+30^0)= {3\over \sqrt { 12} }  $$ then find cos²θ :