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Algebra 2. Chapter 9 Conic Sections: Circles and Parabolas. 9-1 Distance and Midpoint Formulas. WARMUP: Simplify: -5 + 2 5. ( -1 – (-4)) 2 | -2 + (-6) | (3 – (-5)) 2 – ( -4 - 2) 2. 9-1 Distance and Midpoint Formulas.
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Algebra 2 Chapter 9 Conic Sections: Circles and Parabolas
9-1 Distance and Midpoint Formulas • WARMUP: • Simplify: • -5 + 2 5. • ( -1 – (-4))2 • | -2 + (-6) | • (3 – (-5))2 – ( -4 - 2)2
9-1 Distance and Midpoint Formulas • Objective: To find the distance between any two points and the midpoint of the line segment joining them.
9-1 Distance and Midpoint Formulas • Chapter 9 has a subtitle of “Conic Sections”. • http://clem.mscd.edu/~talmanl/HTML/ConicSections.html
9-1 Distance and Midpoint Formulas • How do we tell the distance between any two points on a number line?
9-1 Distance and Midpoint Formulas • The distance between any two points P and Q is written PQ. On a number line, PQ is the absolute value of the difference between their coordinates. • Since | a – b | = | b – a | order doesn’t matter. • Example:
9-1 Distance and Midpoint Formulas • What about two points in a coordinate plane? • Pick two points…
9-1 Distance and Midpoint Formulas • Reminder: Pythagorean Theorem: If the length of the hypotenuse of a right triangle is c, and the lengths of the other two sides (legs) are a and b, then
9-1 Distance and Midpoint Formulas • The Distance Formula: The distance between the points and is:
9-1 Distance and Midpoint Formulas • Find the distance between: • points: ( -2, -1 ) and ( -4, 3 ) • points: ( 2, -7 ) and ( 2, -1 )
9-1 Distance and Midpoint Formulas • The distance formula can be used to prove the Midpoint Formula: • The Midpoint Formula: The midpoint (M) of the line segment joining and is
9-1 Distance and Midpoint Formulas • Find the midpoint of the line segment joining the points: • ( 4, -6 ) and ( -3, 2 ) • ( 7, 5 ) and ( -1, -3 )
9-1 Distance and Midpoint Formulas • Typical test question: • Find the coordinates of Q given that M is the midpoint of the line segment PQ: P( 0, 0 ), M( 3, 5 ) Can do it graphically. On a test you MUST do it mathematically…
9-1 Distance and Midpoint Formulas • More examples:
9-1 Distance and Midpoint Formulas • Homework: