All ACT Math Resources
Example Questions
Example Question #2 : Coordinate Geometry
Which line passes through the points (0, 6) and (4, 0)?
y = 2/3x –6
y = 2/3 + 5
y = 1/5x + 3
y = –3/2 – 3
y = –3/2x + 6
y = –3/2x + 6
P1 (0, 6) and P2 (4, 0)
First, calculate the slope: m = rise ÷ run = (y2 – y1)/(x2 – x1), so m = –3/2
Second, plug the slope and one point into the slope-intercept formula:
y = mx + b, so 0 = –3/2(4) + b and b = 6
Thus, y = –3/2x + 6
Example Question #1 : Distance Formula
Let W and Z be the points of intersection between the parabola whose graph is y = –x² – 2x + 3, and the line whose equation is y = x – 7. What is the length of the line segment WZ?
7√2
4√2
4
7
7√2
First, set the two equations equal to one another.
–x² – 2x + 3 = x – 7
Rearranging gives
x² + 3x – 10 = 0
Factoring gives
(x + 5)(x – 2) = 0
The points of intersection are therefore W(–5, –12) and Z(2, –5)
Using the distance formula gives 7√2
Example Question #2 : Distance Formula
In an xy-plane, what is the length of a line connecting points at (–2,–3) and (5,6)?
7.5
9.3
12.5
11.4
11.4
Use the distance formula:
D = √((y2 – y1)2 + (x2 – x1)2)
D = √((6 + 3)2 + (5 + 2)2)
D = √((9)2 + (7)2)
D = √(81 + 49)
D = √130
D = 11.4
Example Question #1 : Distance Formula
What is the distance between points and , to the nearest tenth?
The distance between points and is 6.4. Point is at . Point is at . Putting these points into the distance formula, we have .
Example Question #1 : Distance Formula
What is the slope of the line between points and ?
The slope of the line between points and is . Point is at . Point is at . Putting these points into the slope formula, we have .
Example Question #3 : Distance Formula
What is the distance between and ?
Let and and use the distance formula: . The distance formula is a specific application of the more general Pythagorean Theorem: .
Example Question #4 : Distance Formula
What is the distance, in coordinate units, between the points and in the standard coordinate plane?
The distance formula is , where = distance.
Plugging in our values, we get
Example Question #5 : Distance Formula
What is the distance between points and ?
Solution A:
Use the distance formula to calculate the distance between the two points:
Solution B:
Draw the two points on a coordinate graph and create a right triangle with sides 4 and 5. Using the Pythagorean Theorem, solve for the hypotenuse or the distance between the two points:
Example Question #6 : Distance Formula
What is the distance between (1,5) and (6,17)?
Let and
So we use the distance formula
and evaluate it using the given points:
Example Question #2 : Distance Formula
What is the area of a square with a diagonal that has endpoints at (4, –1) and (2, –5)?
10
20
5
100
25
10
First, we need to find the length of the diagonal. In order to do that, we will use the distance formula:
Now that we have the length of the diagonal, we can find the length of the side of a square. The diagonal of a square makes a 45/45/90 right triangle with the sides of the square, which we shall call s. Remember that all sides of a square are equal in length.
Because this is a 45/45/90, the length of the hypotenuse is equal to the length of the side multiplied by the square root of 2
The area of the square is equal to s2, which is 10.