Trigonometry

Right angled triangles and Phythagoras’ Theorem

$c² = a² + b²$

• So:
  • $c = √a² + b²$
  • $a = √c² + b²$
  • $b = √c² + a²$

Right angled triangles and the Trigonometric ratios

• $Sin A = opposite/hypotenuse$
• $Cos A = adjacent/hypotenuse$
• $Tan A = opposite/adjacent$
• / means over

• $Opposite$ = The side opposite the acute angle
• $Hypotenuse$ = side opposite right angle
• $Adjacent$ = the remaining side beside the acute angle

Finding angles

Example:

1. Sin A = opposite/hypotenuse so Sin A = 3/7
2. Put Sin^-1(3/7) into the calculator to get 25.37.. which rounds to 25 degrees
3. A = 25 degrees