Trigonometric identities

• sin(0)

  0
• sin(30)

  $\frac{1}{2}$
• sin(60)

  $\frac{\sqrt{3}}{2}$
• sin(45)

  $\frac{\sqrt{2}}{2}$
• sin(90)

  1
• cos(0)

  1
• cos(30)

  $\frac{\sqrt{3}}{2}$
• cos(45)

  $\frac{\sqrt{2}}{2}$
• cos(60)

  $\frac{1}{2}$
• cos(90)

  0
• tan(0)

  0
• tan(30)

  $\frac{\sqrt{3}}{3}$
• tan(45)

  1
• tan(60)

  $\sqrt{3}$
• tan(90)

  not defined
• $\frac{4}{0}$$\rightarrow$$\infty$

  → means tends to

  ∞ means infinity
• $\tan$$=$$\frac{\sin}{\cos}$

  tan = sin / cos
• Identity - something that is always true.
• $\frac{1}{\tan}$$=$$\frac{\cos}{\sin}$

  1 / tan = cos / sin
• $\sin^2+$$\cos^2=$$1$

  sin^2 + cos^2 = 1