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: Explain why a fraction a/b is equivalent to a fraction (n × a)/(n × b) by using visual fraction models, with attention to how the number and size of the parts differ even though the two fractions themselves are the same size. Use this principle to recognize and generate equivalent fractions.
Grade 4 expectations in this domain are limited to fractions with denominators 2, 3, 4, 5, 6, 8, 10, 12, and 100.
problem_activity: Problem 1
a.   Solve.
10
$$\times$$
23 = ___________
10
$$\times$$
450 = ___________
10
$$\times$$
10,870  = ___________
b.   What do you notice about Part (a)? What do you wonder?
c.   Use your conclusions from Part (b) to find the solutions below.
___________
$$\times$$
10 = 5,090
60,200
$$\div$$
10 = ___________
___________
$$\div$$
10 = 3,050
20,008
$$\times$$
___________ = 200,080
Problem 2
There are about 39,000 fourth graders in Mississippi and about 390,000 fourth graders in Texas. There are about 3,900,000 fourth graders in the United States.
a.   How many times more fourth graders are there in Texas than in Mississippi? How many times more fourth graders are there in the United States than in Texas?
b.   There are about 3,900 fourth graders in Boston, MA. How many times more fourth graders are there in the United States than in Boston?


aligns: no