Hi

Need to KNOW: cos (-θ) =cos( θ)  and sin(-θ) = -sin θ and tan(-θ) = - tan θ

cos(-π/4) = cos(π/4)= √2/2  

csc(-π/4) = 1/cos(π/4)=  2/√2 = √2



cot( -π/4 )  = cos (-π/4)/sin(-π/4) = (√2/2)/(-√2/2) =  -1

...............

θ	radians	sin θ	cos θ	tan θ

0°	0	0	1	0

30°	π/6	1/2	√3/2	√3/3

45°	π/4	√2/2	√2/2	1

60°	π/3	√3/2	1/2	√3

90°	π/2	1	0	─

 

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