Evaluate me following without a calculator 19sin21080 41cos

Evaluate me following without a calculator. 19sin^2(-1080) - 41cos^2(1170) = 58sec(-540) + tan(720) - 16csc(450) =

a) 19 sin² ( -1080) - 41 cos²(1170)

sin² ( -1080) = [sin(-1180)]² = [ - sin (1180)]² =[ - sin( - 360*3 + 0)]² = - sin 0 = 0

[ formula used , sin ( -x) = -sin x , sin ( n.2 pi +x ) = sin x]

cos²(1170) = [ cos (1170 ) ]² = [cos ( 360*3 + 90)] ²= [ cos 90]² = 0

so 19 sin² ( -1080) - 41 cos²(1170) = 19* 0 - 41* 0 = 0

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b) 58 sec( -540) + tan(720) - 16 cosec(450)

sec( - 540) = sec( 540) [ sec( -x) = sec x ]

sec( 540) = sec( 360*1+ 180) = sec 180 = -1

tan( 720) = ( 360*2 + 0) = tan 0 = 0

cosec ( 450) = cosec( 360*1+ 90) = cosec 90 = 1

so 58 sec( -540) + tan(720) - 16 cosec(450) = 58*-1 + 0 -16*1 = -74