Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
8. Coordinate Proofs
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Exercise 16 Page 643

Calculate the length of OT with the Distance Formula.

Unlabeled vertices: O(0,0), U(k,0), R(k,k), R(k,2k), T(2k,2k)
OT = ksqrt(8)

Practice makes perfect

Let's start by finding the y-coordinates of the unlabeled vertices.

Both O and U are on the x-axis so their y-coordinate is 0. Also, S and T are 2k above the x-axis which must mean they have y-coordinates of 2k. Finally, since R bisects SU, we know that R must have a y-coordinate that is half of 2k.

Next, we will find the x-coordinates of our points. Since O is at the origin, it's x-coordinate must be 0. Also, since OU=UR=RS=ST, we know that the points along SU have x-coordinates of k and T has an x-coordinate of 2k.

When we know the coordinates of O and T, we can calculate the length of OT with the Distance Formula.
d = sqrt((x_2 - x_1)^2 + (y_2 - y_1)^2)
d_(OT) = sqrt(( 2k - 0)^2 + ( 2k - 0)^2)
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Simplify right-hand side
d_(OT) = sqrt((2k)^2 + (2k)^2)
d_(OT) = sqrt(4k^2 + 4k^2)
d_(OT) = sqrt(8k^2)
d_(OT) = ksqrt(8)