" 11."(cos A)/(1+sin A)=tan(45^(@)+-(A)/(2))

Prove that (cos A )/( 1 - sin A ) = tan (45 ^(@) + (A)/(2)),

sin (45 ^ (@) + A) sin (45 ^ (@) - A) = (1) / (2) cos2A

Evaluate : (i) cos^(2) 25^(@) - sin^(2)65^(@) - tan^(2)45^(@) (ii) ((sin 77)/(cos 13))^(2) + ((cos 77)/(sin 13))^(2) - 2 cos^(2) 45^(@)

Prove that : (tan A + (1)/ (cos A))^(2) + (tan A - (1)/ (cos A))^(2) = 2 ((1 + sin^(2) A)/ (1 - sin^(2) A))

If x sin 45^(@) cos 45^(@) tan60^(@)=tan^(2)45^(@) -cos60^(@) , then determine the value of x.

The value of sin^(2) 60^(@) + 2 tan 45^(@) - cos^(2) 30^(@) is :

The numerical value of ( cos^2 45^@ ) /( sin ^2 60 ^@) +( cos ^2 60^@ )/( sin ^2 45 ^@ ) -(tan ^2 30 ^@ )/( cot^2 45^@ ) -( sin^2 30 ^@ )/( cot^2 30^@) is

What is the value of (1/(sin45^@)-sin45^@) (1/(cos 45^@)-cos45^@)(tan45^@+1/(tan45^@)) ?

sin225^(@)=sin(180^(@)+45^(@))=-sin45^(@)=-(1)/(sqrt(2)) cos246^(@)=cos(180^(@)+66^(@))=-cos66^(@)=-0.4067 tan211^(@)=tan(180^(@)+31^(@))=tan31^(@)=0.6009 .