Classifying Triangles in the Coordinate Plane

Teacher Chang explains how to classify triangles in the coordinate plane by their angles and sides. The video covers acute, right, and obtuse triangles, as well as equilateral, isosceles, and scalene triangles. The Pythagorean relation is used to determine the type of triangle based on side lengths. Two examples are provided: one using a coordinate plane and another using given coordinates to classify triangles using the distance formula and Pythagorean theorem.

What type of triangle has all angles less than 90 degrees?

• Isosceles triangle

• Acute triangle

• Right triangle

• Obtuse triangle

Which triangle has one angle exactly equal to 90 degrees?

• Acute triangle

• Scalene triangle

• Equilateral triangle

• Right triangle

In an equilateral triangle, how many degrees does each angle have?

• 90 degrees

• 60 degrees

• 180 degrees

• 45 degrees

Which statement is true for an isosceles triangle?

• No sides are congruent

• Exactly two sides are congruent

• All sides are congruent

• All angles are 90 degrees

Using the distance formula, what is the first step in finding the length of side AB?

• Divide the coordinates

• Add the coordinates

• Subtract the coordinates

• Multiply the coordinates

What does the Pythagorean theorem state for a right triangle?

• A squared times B squared equals C squared

• A squared plus B squared equals C squared

• A squared minus B squared equals C squared

• A squared plus B squared equals C cubed

If side AB is congruent to side BC in triangle ABC, what type of triangle is it at minimum?

• Acute

• Equilateral

• Isosceles

• Scalene

What does it indicate if the square root of 180 squared equals the sum of the squares of the other two sides?

• It's an obtuse triangle

• It's an acute triangle

• It's a right triangle

• It's a scalene triangle

What is the length of side GH if the coordinates are (-4,0) and (4,0)?

• 8 units

• 12 units

• 4 units

• 16 units

If all sides of a triangle are 8 units, what type of triangle is it?

• Right

• Equilateral

• Scalene

• Isosceles