Triangle Area and Angle Concepts

This video tutorial explains how to calculate the area of a triangle using Heron's formula when all three sides are known. It also covers the calculation of the semi-perimeter and demonstrates the use of the side-angle-side formula for oblique triangles. The tutorial includes examples to illustrate these methods, providing a comprehensive understanding of triangle area calculations.

What is the first step in using Heron's formula to find the area of a triangle?

• Measure the angles of the triangle

• Determine the type of triangle

• Find the semi-perimeter of the triangle

• Calculate the height of the triangle

If the sides of a triangle are 7, 6, and 5, what is the semi-perimeter?

• 18

• 13

• 11

• 9

In Heron's formula, what operation is performed after finding the semi-perimeter?

• Add the semi-perimeter to each side

• Multiply the semi-perimeter by each side

• Subtract each side from the semi-perimeter

• Divide the semi-perimeter by each side

What is the approximate decimal value of the area calculated using Heron's formula for sides 7, 6, and 5?

• 10.8

• 16.3

• 14.7

• 12.5

Which formula is used to calculate the area of a triangle when two sides and the included angle are known?

• SAS formula

• Heron's formula

• Law of Sines

• Pythagorean theorem

What is the key requirement for using the SAS formula to find the area of a triangle?

• The triangle must be right-angled

• Two sides and the included angle must be known

• The triangle must be isosceles

• All three sides must be equal

In the SAS formula, what does the 'S' stand for?

• Square

• Sine

• Side

• Sum

If side a is 20, side b is 25, and angle C is 30 degrees, what is the area of the triangle using the SAS formula?

• 175 square units

• 100 square units

• 150 square units

• 125 square units

What is the sine of a 30-degree angle?

• 1

• 0.5

• 0.75

• 0.25

Which of the following is NOT a valid form of the SAS formula?

• 1/2 bc sin A

• 1/2 ab sin C

• 1/2 ab cos C

• 1/2 ac sin B