Addition and subtraction trig identities

The  exercise appears under the Trigonometry Math Mission. This exercise introduces the angle sum and difference formulas, and by extension, discovers the double angle formulas.

Types of Problems
There are two types of problems in this exercise:


 * 1) Find the value of the angle sum: This problem asks the student to find the value of a trig function of an angle sum or difference. The student is expected to use that formula to find the value and write it in the space provided.Aasti1.png
 * 2) Find the value of the double: This problem asks the student to find the value of a trig function of a double angle. The student is expected to use that formula to find the value and write it in the space provided.Aasti2.png

Strategies
Knowledge of the angle addition and double angle formulas are encouraged beforehand to ensure success on this exercise.
 * 1) The sine formulas for addition and subtraction are $$ sin(x\pm y)=sin(x)cos(y)\pm cos(x)sin(y)$$.
 * 2) The cosine formulas for addition and subtraction are $$ cos(x\pm y)=cos(x)cos(y)\mp sin(x)sin(y)$$.
 * 3) The double angle formulas are $$ sin(2x)=2sin(x)cos(x)$$ and $$cos(2x)=cos^2(x)-sin^2(x)$$.

Real-life Applications

 * 1) Manipulation of trigonometric expressions is important for being able to prove identities and solve equations with trigonometric functions.
 * 2) Trigonometry itself has several applications in physics regarding motion.