If the ratio of the length of AP to PB is 3:7, then the sum of their lengths will be 10 units.
P(- 0.2,2.2)
Practice makes perfect
A ratio of 3 to 7 indicates that for every 3 of one thing, 7 of another thing will occur. To compare the lengths of the two line segments, AP and PB, let's say that they are made of units of length x.
We see here that AP is of length 3x, while PB is of length 7x, thus fulfilling our ratio of 3: 7. If we combine these two segments into one collinear segment, we can form the segment AB.
Therefore, the point P is 3 out of 10 steps between A and B. Now let's draw the segment AB in a coordinate plane using the given coordinates for A(- 2,1) and B(4,5).
To move from A to P, we need to move 310ths of the way from A to B in both the vertical and horizontal directions. To calculate this, we need to find the segment's slope. Remember to leave the slope in terms of "rise" and "run" and do not simplify.
Knowing the slope, we can write equations for finding the x- and y-coordinates of P using the "rise" and "run" separately.
&Rise:& 3/10* 4= 1.2 [0.8em]
&Run:& 3/10* 6= 1.8
We have to move 1.8 steps in the positive horizontal direction and 1.2 steps in the positive vertical direction to move from point A to point P.
