this is for the Sin
*Remember that sin = opposite / hypotenuse*
a² + b² = c² (where a and b are legs and c is the hypotenuse)
From the picture, you can see:
a = 3
c = 4
Plug these into the equation and solve for b.
* a² + b² = c² *
step 1: 3² + b² = 4²
step 2: 9 + b² = 16
step 3: b² = 16 - 9
step 4: b² = 7
step 5: √(b²) = √7
step 6: b = ± √7
FOR COS:
From the picture, you can see that if θ is in quadrant II, b has to be negative.
b = -√7 = adjacent
Remember that cos θ = adjacent / hypotenuse.
cos θ = adjacent / hypotenuse
cos θ = (-√7 / 4)