few_shots: 
Example:
Concept/skill: 
Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems.

Problem/activity:
Find the general solution for:
$${\mathrm{cos}\left({\pi\over2}+x\right)=\mathrm{tan}{\pi\over4}}$$


Answer: 
Yes. An initial step when solving for x in this problem requires the use of the addition formula for cosine on the left side of the equation.

Now, determine whether the following problem or activity can enable students to understand the concepts or skills in the provided description.

shot_info: fl_problem_001894_pos_0

HS_0
standard_description: Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Task
Write as many equations for each picture as you can.
Use the numbers 4, 1, and 5.
[IMG]
Here are some equations for this picture. $$4+1=5 \hskip4em 5 = 4+1$$ $$5-1=4 \hskip4em 4=5-1$$ Can you find more equations?
Use the numbers 3, 5, and 8.
[IMG]
Use the numbers 4, 4, and 8.
[IMG]
Use the numbers 4, 5, and 9.
[IMG]
Draw your own picture and write all the equations you can think of to describe it.


aligns: yes