standard_description: Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems.
problem_activity: Task
State the meaning of each of the following expressions and draw a picture that represents it.
$$(3\times5)+4$$
$$3\times(5+4)$$
State the meaning of this expression:
$$3\times5+4$$
How do you know?
State the meaning of each of the following expressions and draw a picture that represents it.
$$(3+5)\times4$$
$$3+(5\times4)$$
State the meaning of this expression:
$$3+5\times4$$
How do you know?


aligns: no