Section 3.2 Connections to Algebra
In algebra, you learned a system of two linear equations in x and y can have exactly one solution, no solutions, or infinitely many solutions. Geometrically, this means : Intersecting Lines Parallel Lines Coincident Lines
Postulate 12 If two distinct lines intersect, then their intersection is exactly one point. (think systems of equations)
Postulate 13 Parallel Postulate If there is a line and a point not on the line, then there is exactly one line through the point parallel to the given line. b ● a
Example: Line 1 is given by Line 2 is parallel to Line 1 and passes through the point (3,2). Write the equation for Line 2.
Example 2: is given by is parallel to and passes through the point (1,-1). Write the equation for.
Postulate 14 Perpendicular Postulate If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the given line. ● a
Example: Write the equation of the line which passes through (-1,3) and is perpendicular to Example 2: is given by is perpendicular to and passes through the point (5, -3). Write the equation for.
More Examples: 1. Solve the following system of equations: x – 2y = -7 3x + 4y = 9 2. Find the equation of a line that is parallel to y = -3x + 2 and passes through the point (2,1). 3. Find the equation of a line that is perpendicular to y = -2x + 1 and passes through the point (4,0).
More Examples: 4. Write the equation of the line through (-3,2) and (-1,-4). 5. Write in standard form. 6. Write the equation of the line through (-4,4) and (-2,-3) in standard form. 7. Write the equation of the line through (4,9) and (4,5). 8. Write the equation of the line through (-4,-1) and (12,-1).