All SSAT Upper Level Math Resources
Example Questions
Example Question #15 : How To Find The Equation Of A Curve
A horizontal parabola on the coordinate plane includes points , and .
Give its equation.
The standard form of the equation of a horizontal parabola is
If the values of and from each ordered pair are substituted in succession, three equations in three variables are formed:
The three-by-three linear system
can be solved by way of the elimination method.
can be found first, by multiplying the first equation by and add it to the second:
Substitute 5 for in the last two equations to form a two-by-two linear system:
The system
can be solved by way of the substitution method;
Substitute 2 for in the top equation:
The equation is .
Example Question #241 : Coordinate Geometry
Give the equation of the above circle.
None of the other choices is correct.
A circle with center and radius has equation
The circle has center and radius 5, so substitute:
Example Question #242 : Coordinate Geometry
A circle on the coordinate plane has a diameter whose endpoints are and . Give its equation.
A circle with center and radius has equation
The midpoint of a diameter of the circle is its center, so use the midpoint formula to find this:
Therefore, and
The radus is the distance between the center and one endpoint, so take advantage of the distance formula using and . We will concern ourcelves with finding the square of the radius :
Substitute:
Example Question #243 : Coordinate Geometry
Give the equation of the above circle.
A circle with center and radius has equation
The circle has center and radius 4, so substitute:
Example Question #3 : Circles
A circle on the coordinate plane has a diameter whose endpoints are and . Give its equation.
A circle with center and radius has equation
The midpoint of a diameter of the circle is its center, so use the midpoint formula to find this:
Therefore, and .
The radus is the distance between the center and one endpoint, so take advantage of the distance formula using and . We will concern ourcelves with finding the square of the radius :
Substitute:
Expand:
Example Question #2 : How To Find The Equation Of A Circle
A circle on the coordinate plane has center and circumference . Give its equation.
A circle with center and radius has equation
The center is , so .
To find , use the circumference formula:
Substitute:
Example Question #251 : Coordinate Geometry
A circle on the coordinate plane has center and area . Give its equation.
A circle with center and radius has the equation
The center is , so .
The area is , so to find , use the area formula:
The equation of the line is therefore:
Example Question #7 : Circles
What is the equation of a circle that has its center at and has a radius of ?
The general equation of a circle with center and radius is:
Now, plug in the values given by the question:
Example Question #2 : Circles
If the center of a circle with a diameter of 5 is located at , what is the equation of the circle?
Write the formula for the equation of a circle with a given point, .
The radius of the circle is half the diameter, or .
Substitute all the values into the formula and simplify.
Example Question #9 : How To Find The Equation Of A Circle
Give the circumference of the circle on the coordinate plane whose equation is
The standard form of the equation of a circle is
where is the radius of the circle.
We can rewrite the equation we are given, which is in general form, in this standard form as follows:
Complete the squares. Since and , we do this as follows:
, so , and the circumference of the circle is
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