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DISTANCE FROM A POINT TO A LINE. (X , Y) TO Y = AX + B. http://www.youtube.com/watch?v=iATjsfAX8yc. KHAN ACADEMY VIDEO. WHAT DO WE KNOW ABOUT PERPENDICULAR LINES (p 97) Find the slope of the point to the line a x a‘ = -1 Example: y = ax + b is perpendicular to
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DISTANCE FROM A POINT TO A LINE (X , Y) TO Y = AX + B
http://www.youtube.com/watch?v=iATjsfAX8yc KHAN ACADEMY VIDEO
WHAT DO WE KNOW ABOUT PERPENDICULAR LINES (p 97) • Find the slope of the point to the line a x a‘ = -1 • Example: y = ax + b is perpendicular to y = a’x + b y = -2x + 4 is perpendicular to y = 1/2x + 3/2 STEP 1: PERPENDICULAR LINES
2nd step. Find the intercept (b) • Straight substitution y = 1/2x + b (7, 5) 5 = 1/2(7) + b 5 – 7/2 = b 3/2 = b • y = 1/2x + 3/2 STEP 2: SLOPE & POINT
Next step: Compare the two equations -2x + 4 = 1/2x + 3/2 4 – 3/2 = 1/2x + 2x 5/2 = 2.5x 1 = x (1, y) find for y y = 1/2x + 3/2 or y = ½(1) + 3/2 y = 2 Our point on the line is (1, 2) STEP 3: COMPARISON METHOD
Our two points A (7, 5) and B (1, 2) d = (x2 - x1)2 + (y2 – y1)2 (7 – 1)2 + (5 – 2)2 62 + 32 36 + 9 45 = 6.7082 STEP 4: MEASURE DISTANCE BETWEEN 2 POINTS
d(P, l) = STEP 5: FORMULA