Math Problem Statement

A manufacturer cuts a piece of metal for a microscope. The resulting piece of metal can be represented in a coordinate plane by a triangle with vertices A(0, 0), B(3, 8), and C(6, 0). One unit in the coordinate plane represents one millimeter. Prove that △ABC is isosceles. Find the exact length of each side.

Solution

The problem involves proving that the triangle ABC\triangle ABC, with vertices A(0,0)A(0, 0), B(3,8)B(3, 8), and C(6,0)C(6, 0), is isosceles and finding the exact lengths of its sides.

Step 1: Find the lengths of the sides using the distance formula.

The distance formula between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is: d=(x2x1)2+(y2y1)2.d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}.

1. Length of ABAB:

Using A(0,0)A(0, 0) and B(3,8)B(3, 8): AB=(30)2+(80)2=32+82=9+64=73.AB = \sqrt{(3 - 0)^2 + (8 - 0)^2} = \sqrt{3^2 + 8^2} = \sqrt{9 + 64} = \sqrt{73}.

2. Length of BCBC:

Using B(3,8)B(3, 8) and C(6,0)C(6, 0): BC=(63)2+(08)2=32+(8)2=9+64=73.BC = \sqrt{(6 - 3)^2 + (0 - 8)^2} = \sqrt{3^2 + (-8)^2} = \sqrt{9 + 64} = \sqrt{73}.

3. Length of ACAC:

Using A(0,0)A(0, 0) and C(6,0)C(6, 0): AC=(60)2+(00)2=62+02=36=6.AC = \sqrt{(6 - 0)^2 + (0 - 0)^2} = \sqrt{6^2 + 0^2} = \sqrt{36} = 6.

Step 2: Prove ABC\triangle ABC is isosceles.

An isosceles triangle has at least two equal sides. From the above calculations:

  • AB=73AB = \sqrt{73},
  • BC=73BC = \sqrt{73},
  • AC=6AC = 6.

Since AB=BCAB = BC, ABC\triangle ABC is isosceles.


Final Answer:

  1. The exact lengths of the sides are:
    • AB=73AB = \sqrt{73},
    • BC=73BC = \sqrt{73},
    • AC=6AC = 6.
  2. ABC\triangle ABC is isosceles because AB=BCAB = BC.

Would you like a deeper explanation of the distance formula, or assistance visualizing this triangle on a coordinate plane?


Related Questions:

  1. What is the perimeter of ABC\triangle ABC in millimeters?
  2. How can you calculate the area of ABC\triangle ABC using its coordinates?
  3. Can this isosceles triangle ever be classified as equilateral? Why or why not?
  4. What are the slopes of the sides ABAB, BCBC, and ACAC?
  5. How does the coordinate system influence the physical dimensions of the triangle?

Tip:

When proving a triangle is isosceles, always compare the exact lengths of its sides carefully using the distance formula!

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangles
Coordinate Geometry

Formulas

Distance Formula: d = √((x2 - x1)^2 + (y2 - y1)^2)

Theorems

Properties of Isosceles Triangles

Suitable Grade Level

Grades 8-10