Introduction to Trigonometry

What is Trigonometry? Trigonometry is the study of how the sides and angles of a triangle are related to each other. It's all about triangles!

A Right Triangle Opposite Hypotenuse Adjacent

Same Right Triangle – Different Angle Hypotenuse B Adjacent Opposite

Trig Definitions: Sine = opposite/hypotenuse Cosine = adjacent/hypotenuse Tangent = opposite/adjacent Cosecant = hypotenuse/opposite Secant = hypotenuse/adjacent Cotangent = adjacent/opposite

A Way To Remember Sin = Opposite/Hypotenuse Oprah Had Cos = Adjacent/Hypotenuse A Huge Tan = Opposite/Adjacent Old Afro

y x y x r O x,y r = x + y 222

Definitions of Trig Functions Sin =y / r Cos =x / r Tan =y / x Csc=r / y Sec=r / x Cot= x / y O O O O O O

Radius = 1 The Unit Circle

y x 1/2 30 x,y r = x + y √3/2

y x √/2/2 45 x,y r = x + y √2/2

y x 1/2 60 x,y r = x + y √3/2

The Unit Circle-Special Angles and Their Exact Values