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High School Archive

Browse High School Coordinate Plane Geometry

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Locus and Equations of Lines [01/10/1999]

Describe the locus of points that are 3 units from the line x = -1...

Locus of the Midpoint of a Chord [03/13/1998]

Show that the locus of the midpoint of the chord is a hyperbola.

Midpoint Formula and Trisection Points [09/05/2003]

Show that ((1/3)(2x_1+ x_2), (1/3)(2y_1+y_2)) is one of the points of trisection of the line segment joining (x_1,y_1) and (x_2,y_2).

Midpoint Formula for any Fraction [01/26/1999]

Is there a formula similar to the midpoint formula to find "any fractional part" of the line from P1 to P2?

Midpoint of a Straight Line Segment [5/7/1996]

What is the midpoint of this: (-3,4) (5,-4)? Use the distance formula.

Minimum Distance from a Point to a Line [7/10/1995]

Find all the values of b such that the minimum distance from the point (2,0) to the line y = 4/3x+b is 5.

Nonconvex Polygon Angle Measure [02/03/1999]

What is the formula to find the interior angle measurements of a nonconvex polygon?

Ordered Pairs vs. Coordinates [9/9/1996]

What is the difference between an ordered pair and coordinates?

Order of Quadrant Numbers [10/21/2002]

Why are quadrants numbered that way?

Overlapping Polygons [06/10/2003]

Given all the coordinates for two different polygons in an x,y plane, how can I determine whether the polygons overlap?

Pick's Formula [05/22/1997]

What is Pick's Formula?

Pick's Theorem, Lattice Points, and Area [08/27/1998]

What is a lattice point, and how does it relate to the area of a triangle, rectangle, and a circle?

Point Inside or Outside Triangle? [08/02/2001]

I have coordinates of three vertices of the triangle and coordinates of the point.

Point on an Ellipse [05/16/1997]

Given an ellipse and an arbitrary angle theta from either axis, how do you find the coordinates of the intersection of the ellipse and a vector formed by angle theta?

Point on a Plane [06/13/1997]

If I know the coordinates of three points that form a plane and the first two coordinates of another point on that plane, how do I find the third coordinate of that point?

Point Reflected in a Plane [6/7/1995]

How do I find the coordinates of point p' which is the reflection of point p in the plane E?

Programming the Distance Formula [03/26/2001]

I want to write a computer program to find the point on a line that's a distance X from a given point not on the line. Can you help?

Proof of Perpendicularity [10/23/1999]

How can you prove that two lines (neither vertical) are perpendicular if and only if the product of the gradients is equal to -1?

A Proof using Analytic Geometry [02/24/1999]

Prove that, if p is a point inside the ellipse, there is one and only one chord QP bisected at P.

Proof Using Coordinate Geometry [06/08/2001]

In equilateral triangle ABC, a segment is drawn from point A to the side BC at a point (D)... prove that angle BFC (or EFC) is a right angle.

Proving Diagonals Perpendicular [07/28/2003]

Given the points a(-4,1), b(2,3), c (4,9) and d (-2,7), show that quadrilateral abcd is a parallelogram with perpendicular diagonals.

Quadrant [03/25/2001]

What is a quadrant?

Quadrilateral Area [04/29/2002]

Given the (x,y) coordinates of four points, is there a simple formula to compute the area of the quadrilateral with corners on these 4 points?

Radius and Center of a Circle from 3 Points [07/23/1999]

Given the coordinates of three points on a circle, how can you find the center and radius?

Radius, Center of Circle Given 3 Points [8/28/1996]

What is an easy formula to calculate the center point and radius of a circle given three points on the circumference?

A Right Triangle of Points [01/14/1999]

Determine the values of x that would make the points (x,0), (-2,1), and (3,4) the vertices of a right triangle.

Similar Triangles [1/22/1996]

For triangle ABC whose vertices are A(6,3),B(1,5),C(-1,4), what are the vertices of a similar triangle whose perimeter is 5 times that of triangle ABC?

A Slope Problem Involving a Billiards Table [10/19/2004]

Suppose that a square billard table has corners at (0,0),(1,0),(1,1), (0,1). A ball leaves the origin along a line with slope s. If the ball reaches a corner, it stops or falls in. Whenever it hits the side of the table not at a corner, it continues to travel on the table, but the slope on the line is multiplied by -1. Does the ball reach a corner?

Solve for Radius [09/09/1997]

Given a circle through three points, what is the equation for the intersection of the perpendicular bisectors?

Tangent Common to Two Ellipses [10/24/2002]

I have two general ellipses in space and I want to find the equation of the tangent common to these ellipses.

Theta [04/14/1997]

What is Theta? Does it have a constant value?

Using Midpoints to Determine Vertices [09/04/2002]

The midpoints of the sides of a triangle have coordinates G(3,1), H (-1,2) and J (1,-3). Determine the coordinates of the vertices of the triangle.

Using the Cartesian Plane [01/19/1997]

Draw a rectangle that is Sqrt(2) by 1 with corners at (0,0), (1,0), (1,Sqrt(2)), and (0,Sqrt(2)).

Vertex of a Parabola [04/16/2002]

Finding the y-coordinate of the vertex of a parabola.

A Way to Remember What 'm' and 'b' Mean in Slope-Intercept Form [02/01/2004]

An interesting memory trick to help you remember how to graph a linear equation in slope-intercept form.

What is a point? [8/26/1996]

Define a point, please.

When is a Slope 0 or Undefined? [3/29/1997]

How do I know when the slope of an equation is zero or undefined (no slope)?

Where Will the Runners Meet? [03/29/1999]

Two runners, A and B, start 90 degrees away from each other on a circular track and run at the same speed. If Runner B decides to cut across the track, where will they meet?

Why Does dxdy = rdrd(theta)? Why Not Just drd(theta)? [12/29/2009]

In transforming from rectangular form to polar form, I have always memorized dxdy = rdrd(theta) without understanding it....

Why Use h and k for the Center of a Circle? [05/09/2000]

Why are k and h used in the equation (x-h)^2 + (y-k)^2 = 0 for a circle with center (h,k)? Why not j and f, etc.?

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