External Angles in Triangles

The video tutorial explains how to find a missing angle in a triangle. It starts with the basic method of adding the other two angles and subtracting from 180 degrees. However, in this case, an external angle is used. The external angle and the missing angle form a linear pair. By subtracting 126 from 180, the external angle is found to be 54 degrees. Adding 54 and 78 gives 132, which is subtracted from 180 to find the missing angle of 48 degrees.

What is the first step in solving the problem of finding an angle in a triangle?

• Identify the type of triangle.

• Find the length of the sides.

• Determine the known angles.

• Calculate the area of the triangle.

What is the sum of angles in a triangle?

• 360 degrees

• 270 degrees

• 180 degrees

• 90 degrees

What is the typical method to find a missing angle in a triangle?

• Add the known angles and subtract from 180.

• Multiply the known angles.

• Divide the known angles by 2.

• Subtract the known angles from 360.

Why can't the typical method be used directly in this problem?

• The triangle is not a right triangle.

• The triangle has an external angle.

• The triangle is not equilateral.

• One of the angles is missing.

What is an external angle in the context of a triangle?

• An angle that is equal to 180 degrees.

• An angle inside the triangle.

• An angle that is equal to 90 degrees.

• An angle formed by extending a side of the triangle.

How do you find the external angle of a triangle?

• Add the internal angles.

• Subtract the internal angle from 180.

• Multiply the internal angles.

• Divide the internal angle by 2.

What is the relationship between an external angle and the internal angle it is adjacent to?

• They are equal.

• They add up to 90 degrees.

• They add up to 180 degrees.

• They are complementary.

What is the first step in calculating the missing angle using the external angle?

• Add the external angle to 180.

• Divide the external angle by 2.

• Multiply the external angle by 2.

• Subtract the external angle from 180.

What is the value of the external angle calculated in the video?

• 132 degrees

• 126 degrees

• 78 degrees

• 54 degrees

What is the next step after finding the external angle?

• Subtract the external angle from 180.

• Add the external angle to the known angle.

• Add the external angle to 180.

• Subtract the external angle from the known angle.