Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 1 - Section 1.9 - The Coordinate Plane; Graphs of Equations; Circles - 1.9 Exercises - Page 102: 39

Answer

The triangle with vertices $A(0,2)$ $,$ $B(-3,-1)$ and $C(-4,3)$ is isosceles.

Work Step by Step

The vertices of the triangle are $A(0,2)$ $,$ $B(-3,-1)$ and $C(-4,3)$ Use the distance between two points formula, which is $d=\sqrt{(x_{2}-x_{1})^{2}+(y_{2}-y_{1})^{2}}$, to find the distance between each point. Find the distance between points $A$ and $B$: $d_{AB}=\sqrt{(-3-0)^{2}+(-1-2)^{2}}=\sqrt{(-3)^{2}+(-3)^{2}}=\sqrt{9+9}=\sqrt{18}=3\sqrt{2}$ Find the distance between points $B$ and $C$: $d_{BC}=\sqrt{(-4+3)^{2}+(3+1)^{2}}=\sqrt{(-1)^{2}+4^{2}}=\sqrt{1+16}=\sqrt{17}$ Find the distance between points $C$ and $A$: $d_{CA}=\sqrt{(-4-0)^{2}+(3-2)^{2}}=\sqrt{(-4)^{2}+1^{2}}=\sqrt{16+1}=\sqrt{17}$ Since the sides $BC$ and $CA$ have the same length and the length of side $AB$ is different from these other two lenghts, the triangle is isosceles.
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