Area of Triangles

Area of a Triangle

Using Sine Law

Area of a right triangle

• Area = 1/2 x base x height

• Area = 1/2 x AC x BC

• Area = 1/2 x b x a

Multiple Choice

If BC is the base of the given triangle, which of the followings is the height?

• AC

• AB

• None of them

Multiple Choice

If a is the base of the given triangle, which of the followings is the height?

• b

• c

• h

Area of any triangle

Area = 1/2 ab sin C

where a, b are two sides and angle C is their INCLUDED angle

Multiple Choice

Which include angle you have to choose to determine the area of XYZ triangle with the given sides?

• 32⁰

• 50⁰

• 98⁰

Multiple Choice

Which of the followings is true to find the area of ABC triangle?

• Area = 1/2 ab sin A

• Area = 1/2 ac sin B

• Area = 1/2 bc sin C

Multiple Choice

Which of the followings is true to calculate the area of XYZ triangle?

• Area = 1/2 x 9 x 7

• Area = 1/2 x 9 x 7 x sin 32⁰

• Area = 1/2 x 9 x 7 x sin 50⁰

Find the area of XYZ

• Area = 1/2 xy sin Z

• Area = 1/2 x 9 x 7 x sin 32⁰

• Area ≈16.6924568...

• Area = 16.7 (correct to 1 decimal place)

Find the length of PQ if the area of triangle PQR is 70.5 cm².

• Area = 1/2 rq sin P

• 70.5 = 1/2 x r x 16 x sin 36⁰

• r = 70.5 / (8 sin 36⁰)

• r ≈14.992720...

• r = 15 cm

Exercise / HW

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----> Algebra 2 Z.20

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