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## 2.4 – Parallel and Perpendicular Lines

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**Recall…**• Slope = measure of steepness of a particular line/graph of an equation • m = Rise/Run OR**We can also look at slopes of multiple lines**• Parallel ( || ): two lines are considered parallel, if and only if, their rise and run are both the same amount • IE, m1 = m2 • Never intersect**Example. Find an equation, in slope-intercept form, that is**parallel to the line 3x + 2y = 3y – 7 and passes through (1,2). • How do we find the slope of the given line?**Perpendicular ( ): two lines are perpendicular, if and**only if, they are opposite reciprocals OR m1(m2) = -1 • If horizontal and vertical, slopes of undefined and zero must occur • Intersection is 900 angle**Example. Find an equation, in slope-intercept form, that is**perpendicular to the line 3x + y = 7 and passes through the point (-2, 5). • How can we find the given slope? • Same? OR?**Example. Determine if the two lines 3x + y = 2 and x + 3y =**2 are perpendicular, parallel, or neither.**Example. A parallelogram is a quadrilateral formed by two**pairs of opposite parallel sides. Determine if following points form a quadrilateral (vertices listed counter-clockwise). • {(-2,2), (-5,-2), (2, -3), (5,1)}**Assignment**• Pg. 161 • 1-25 even, 33