Unit circle cheat sheet

The unit circle is four numbers repeated with signs. Learn the first quadrant exactly, then use reference angles and quadrant signs for everything else.

Practise trigonometry

Radians & degrees

$18 0^{\circ} = π rad$
$rad = deg \cdot \frac{π}{180}$
$deg = rad \cdot \frac{180}{π}$

First-quadrant exact values

$sin 0 = 0, cos 0 = 1, tan 0 = 0$
$sin \frac{π}{6} = \frac{1}{2}, cos \frac{π}{6} = \frac{3}{2}, tan \frac{π}{6} = \frac{3}{3}$
$sin \frac{π}{4} = cos \frac{π}{4} = \frac{2}{2}, tan \frac{π}{4} = 1$
$sin \frac{π}{3} = \frac{3}{2}, cos \frac{π}{3} = \frac{1}{2}, tan \frac{π}{3} = 3$
$sin \frac{π}{2} = 1, cos \frac{π}{2} = 0, tan \frac{π}{2} undefined$

Quadrant signs

$I: all +$
$II: sin +, csc +$
$III: tan +, cot +$
$IV: cos +, sec +$

Symmetry

$sin (- θ) = - sin θ$ Odd
$cos (- θ) = cos θ$ Even
$sin (π - θ) = sin θ$
$cos (π - θ) = - cos θ$