Question 186·200 Super-Hard SAT Math Questions·Geometry and Trigonometry
In the -plane, which of the following points lies on the circle with equation , where and are constants?
For circle questions in standard form, immediately read the center and radius. Then treat each answer choice as a displacement from the center: compute and (or the equivalent expressions). On a hard SAT item with variables, the key is noticing which option makes those displacements constant (so the distance is fixed), rather than expressions that still contain the variables. ЅАТ рreр by Аnikο.ai
Hints
Find the circle’s center
Rewrite the equation in the form to identify the center. Frоm аniко.ai
Use changes from the center
For each point, compute and (equivalently and ).
Look for values that don’t depend on or
A correct option should make and constant numbers so that their squares can add to 1369.
Desmos Guide
Create sliders and graph the circle
Enter the circle as (x+p)^2+(y-q)^2=1369. If Desmos asks, create sliders for p and q.
Pick specific values for p and q
Set p=1 and q=2 (any values work). The circle will update.
Plot the four candidate points
Enter the four points from the choices (using the same p and q). For example, one point would be (-p+35, q+12).
Check which point lies on the circle and stays on it
See which plotted point lies exactly on the circle. Then change p and q to new values (like p=3, q=-1) and observe which choice still lies on the circle. The one that stays on the circle is the correct answer.
Step-by-step Explanation
Identify the center and radius
The equation
has center and radius .
Rewrite the condition for a point to be on the circle
A point is on the circle exactly when the distance from is 37: © аnікo.aі
So we just need and to be numbers whose squares add to 1369.
Test each option by computing and
Compute and for each option.
-
For , , which depends on , so it is not guaranteed to equal 37.
-
For , , which depends on .
-
For , both and depend on or .
Confirm the one option that works
For :
Then
so this point lies on the circle. Therefore, the correct choice is .