If sin
=5/13
then the ratio of opposite side/hypotenuse
=5/13
By Pythagorean Theorem
If opposite side =5units and
hypotenuse =13 units
(for any units)
then adjacent side=12 units
and
cos=adjacent side over
hypotenuse =12/13
However, we need to note that if the angle is in Quadrant II then the
adjacent side
will actually be a negative value
so
cos= 12/13 for an angle in Q1
or
cos= -12/13 for an angle in Q2
(angle can’t be in Q3 or Q4, since sin > 0)
