Coordinate Geometry
Help Questions
Geometry › Coordinate Geometry
Give the -coordinate of the
-intercept of the graph of the function
The graph of has no
-intercept.
Explanation
The -intercept of the graph of
is the point at which it intersects the
-axis. Its
-coordinate is 0,; its
-coordinate is
, which can be found by substituting 0 for
in the definition:
However, does not have a real value. Therefore, the graph of
has no
-intercept.
In which quadrant does the complex number lie?
Explanation
If we graphed the given complex number on a set of real-imaginary axes, we would plot the real value of the complex number as the x coordinate, and the imaginary value of the complex number as the y coordinate. Because the given complex number is as follows:
We are essentially doing the same as plotting the point on a set of Cartesian axes. We move
units right in the x direction, and
units down in the y direction, which puts us in the fourth quadrant, or in terms of Roman numerals:
Explanation
has as its graph a vertical parabola on the coordinate plane. You are given that
and
, but you are not given
.
Which of the following can you determine without knowing the value of ?
I) Whether the graph is concave upward or concave downward
II) The location of the vertex
III) The location of the -intercept
IV) The locations of the -intercepts, if there are any
V) The equation of the line of symmetry
I and III only
I and V only
I, II, and V only
I, III, and IV only
III and IV only
Explanation
I) The orientation of the parabola is determined solely by the sign of . Since
, the parabola can be determined to be concave downward.
II and V) The -coordinate of the vertex is
; since you are not given
, you cannot find this. Also, since the line of symmetry has equation
, for the same reason, you cannot find this either.
III) The -intercept is the point at which
; by substitution, it can be found to be at
.
known to be equal to 9, so the
-intercept can be determined to be
.
IV) The -intercept(s), if any, are the point(s) at which
. This is solvable using the quadratic formula
Since all three of and
must be known for this to be evaluated, and only
is known, the
-intercept(s) cannot be identified.
The correct response is I and III only.
The chord of a central angle of a circle with area
has what length?
Explanation
The radius of a circle with area
can be found as follows:
The circle, the central angle, and the chord are shown below:

By way of the Isosceles Triangle Theorem, can be proved equilateral, so
, the correct response.
Which of the following are the equations of the vertical asymptotes of the graph of ?
(a)
(b)
(b) only
(a) only
Both (a) and (b)
Neither (a) nor (b)
Explanation
The vertical asymptote(s) of the graph of a rational function such as can be found by evaluating the zeroes of the denominator after the rational expression is reduced.
First, factor the denominator. It is a quadratic trinomial with lead term , so look to "reverse-FOIL" it as
by finding two integers with sum 6 and product 5. By trial and error, these integers can be found to be 1 and 5, so
Therefore, can be rewritten as
Set the denominator equal to 0 and solve for :
By the Zero Factor Principle,
or
Therefore, the binomial factor can be cancelled, and the function can be rewritten as
If , then
, so the denominator has only this one zero, and the only vertical asymptote is the line of the equation
.
True or false: The graph of has as a vertical asymptote the graph of the equation
.
False
True
Explanation
The vertical asymptote(s) of the graph of a rational function such as can be found by evaluating the zeroes of the denominator after the rational expression is reduced.
First, factor the numerator. It is a quadratic trinomial with lead term , so look to factor
by using the grouping technique. We try finding two integers whose sum is and whose product is
; with some trial and error we find that these are
and
, so:
Break the linear term:
Regroup:
Factor the GCF twice:
Therefore, can be rewritten as
Cancel the common factor from both halves; the function can be rewritten as
Set the denominator equal to 0 and solve for :
The graph of therefore has one vertical asymptotes, the line of the equations
. The line of the equation
is not a vertical asymptote.
Give the -coordinate of the
-intercept of the graph of the function
The graph of has no
-intercept.
Explanation
The -intercept of the graph of
is the point at which it intersects the
-axis. Its
-coordinate is 0,; its
-coordinate is
, which can be found by substituting 0 for
in the definition:
However, does not have a real value. Therefore, the graph of
has no
-intercept.
has as its graph a vertical parabola on the coordinate plane. You are given that
and
, but you are not given
.
Which of the following can you determine without knowing the value of ?
I) Whether the graph is concave upward or concave downward
II) The location of the vertex
III) The location of the -intercept
IV) The locations of the -intercepts, if there are any
V) The equation of the line of symmetry
I and III only
I and V only
I, II, and V only
I, III, and IV only
III and IV only
Explanation
I) The orientation of the parabola is determined solely by the sign of . Since
, the parabola can be determined to be concave downward.
II and V) The -coordinate of the vertex is
; since you are not given
, you cannot find this. Also, since the line of symmetry has equation
, for the same reason, you cannot find this either.
III) The -intercept is the point at which
; by substitution, it can be found to be at
.
known to be equal to 9, so the
-intercept can be determined to be
.
IV) The -intercept(s), if any, are the point(s) at which
. This is solvable using the quadratic formula
Since all three of and
must be known for this to be evaluated, and only
is known, the
-intercept(s) cannot be identified.
The correct response is I and III only.
Give the domain of the function
The set of all real numbers
Explanation
The square root of a real number is defined only for nonnegative radicands; therefore, the domain of is exactly those values for which the radicand
is nonnegative. Solve the inequality:
The domain of is
.