1.5 – Midpoint
Midpoint: Point in the middle of a segment A B M
Ex 1: Find the midpoint of the segment. M M 1
Ex 2: Find the midpoint of the numbers without a number line. a.10 and 150 b.34 and 72 c.How did you find the midpoint? = = 53 Added them and then divided by 2
Ex 3: Find the midpoint of AB using a coordinate plane. a. A(5, 6) and B(1, 2) A(5, 6) M(, ) B(1, 2) A B M 34
b. A(–5, 6) and B(1, –2) A(-5, 6) M(, ) B(1, -2) A B M -22
c. Look and compare the x-coordinates then compare the y-coordinates. How can you find the midpoint of any segment without drawing a graph? Add the x’s then divide by 2 Add the y’s then divide by 2
Midpoint Formula:
Ex 4: Use the formula to find the midpoint of A(–4, 3) and B(–8, –9). x1x1 y1y1 x2x2 y2y2
Ex 5: Given the midpoint, M, of the segment, find the indicated measures.
a. MZ = ___________ x + 2 = 2x – 3 2 = x – 3 5 = x 2(5) – 3= 7
b. PR = ___________ 5x – 7 = 3x + 1 2x – 7 = 1 2x = 8 x = 4 5(4)-7 = = 26
Ex 6: Given the midpoint and one endpoint, find the other endpoint.
A (, ) M B A M (2, 1) B (1, 4) 3-2
A (4, 4) M (-1, -2) B (, ) -6-8
A (, ) M (6, 5) B (7, 8) 52
A (-1, 2) M (1, 0) B (, ) 3-2