few_shots: 
Example 1:
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.

Example 2:
Concept/skill: 
Understand that the graph of an equation in two variables is the set of all its solutions plotted in the coordinate plane, often forming a curve (which could be a line).

Problem/activity:
Task
Solve the quadratic equation
$$ x^2 = (2x - 9)^2 $$
using as many different methods as possible.


Answer: 
No. This task does not involve an equation in two variables. There is only one variable, x.

Example 3:
Concept/skill: 
Construct a tangent line from a point outside a given circle to the circle.

Problem/activity:
Task
Suppose $A$ is an angle with vertex $P$, as pictured below:
[IMG]
Draw a circle with center $P$ and with  radius $r \gt 0$.  Explain why the circle
meets each ray of angle $A$ in a single point.  Label these points $Q$ and $R$ respectively.
Draw circles with centers $Q$ and $R$ respectively and radius $r$.  These circles meet at $P$ and a second point to be labelled $B$.
Show that ray $\overrightarrow{PB}$  bisects angle $P$.


Answer: 
No. This task does not involve drawing lines that are tangent to circles. The only line that may be drawn is the ray between points P and B.

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

im_task_000870_neg_0

HS_1

im_task_001160_neg_0

HS_2
standard_description: Use data from a randomized experiment to compare two treatments; use simulations to decide if differences between parameters are significant.
problem_activity: Problem 1
Part A: Predict the shape of the graph at 2,000 trials.
|                                       10 trials                                        |                                       100 trials                                        |                                       533 trials                                        |
|----------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------|
| .. image:: https://d37su8u1z9ynie.cloudfront.net/uploads/2018/06/05/algiiu8_l7_at1.png | .. image:: https://d37su8u1z9ynie.cloudfront.net/uploads/2018/06/05/algiiu8_l7_at1a.png | .. image:: https://d37su8u1z9ynie.cloudfront.net/uploads/2018/06/05/algiiu8_l7_at1b.png |
Part B: At 1,799 trials, the graph looks like this:
[IMG]
The mean of the data is approximately 6, and the standard deviation is 1.7. The blue lines around the graph are what should be the "ideal" normal distribution.
Describe what the mean and the standard deviation mean in terms of this situation.
Problem 2
Match the following distributions with the histograms. Explain your reasoning.
| **           Distribution          ** |                 **           Shape          **                 | **           Mean          ** | **           Standard Deviation          ** |
|---------------------------------------|----------------------------------------------------------------|-------------------------------|---------------------------------------------|
|      **           A          **       |          **           Skewed to the right          **          | **           100          **  |         **           10          **         |
|      **           B          **       | **           Approximately symmetric, mound shaped          ** | **           100          **  |         **           10          **         |
|      **           C          **       | **           Approximately symmetric, mound shaped          ** | **           100          **  |         **           40          **         |
|      **           D          **       |          **           Skewed to the right          **          | **           100          **  |         **           40          **         |
[IMG]


aligns: no