Can you count cos tan and sin in your head. Is it a formula?

For a general angle you couldn't calculate the trigonometric values in your head!

 

However, there are some that are worth remembering.

 

sin(30°) = 1/2     cos(30°) = sqrt(3)/2

sin(60°) = sqrt(3)/2   sin(60°) = 1/2

sin(45°) = cos(45°) = 1/sqrt(2)

 

You can find the corresponding tan by dividing sin by cos  (i.e. tan = sin/cos)

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