Let t = theta for short
For each question below, f(t) = sin(t) and g(t) = cos(t). Find the exact value of each function if t = 60 degrees. Do NOT use a calculator.
(1) g(t)
(2) [g(t)]^2
To find the value of the trigonometric functions of the angles 30, 45, and 60, we use the special 45-45-90 and 30-60-90 triangles:
Special right triangles - Wikipedia, the free encyclopedia
You can also find values of an angle whose sum/difference is two of the mentioned angles using the sum/difference identities.
Plato: I read the entire thread before posting. I thought that the matter is how to find the values of trigonometric functions and that the poster was asking how to find them without using a calculator. The opposite prompt said she knows what the value is, but she left an implication that she doesn't know how to get to it. I know what she means now, sorry for the misunderstanding.
Magentarita: yes, you are right.