Trigonometry investigates the relationship between the sides and the angles in
triangles. These special relationships are used in calculus, engineering and physics. So, it is necessary
to understand and know these relationships.
The Right Triangle and the Pythagorean
A right triangle is one that has a right angle. The side opposite the right angle is called the
hypotenuse and the other two sides are referred to as legs.
The Pythagorean Theorem states the sum of the squares of the legs is equal to the square of the
hypotenuse: a2 + b2 = c2
sine (sin) is the ratio of the side opposite and the hypotenuse
cosine (cos) is the ratio of the side adjacent and the hypotenuse
tangent (tan) is the ratio of the side opposite and the side adjacent
REMEMBER: SOH CAH TOA