EXAMPLE 1

In triangle ABC, if a = 25 cm, b = 52 cm and c = 63 cm. Find the area of triangle ABC.

Solution

In triangle ABC, s = 1/2 (a + b + c) = 1/2 (25 + 52 + 63) = 140 /2 = 70 cms.

EXAMPLE 2

In triangle ABC, if a = 25, b = 12 and ÐC = 51⁰. Find the area of triangle ABC.

Solution

Using SAS type i.e.
    D= 1/2 ab sin C
\ D= 1/2 (25) (12) sin 51⁰
\ D= 116.57 sq. units

EXAMPLE 3

In triangle ABC, if a = 125, b = 123, c = 62. Show that sin B = or 0.96

Solution

Firstly we will find area of triangle ABC by using Hero's formula. Here s = 1/2 (a + b + c) = 155

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Index

3. 1 Solving Right Triangles
3. 2 Law of Cosines
3. 3 Law of Sines
3. 4 The Ambiguous Case of Law of Sines
3. 5 Areas of Triangles
Supplementary Problems

Chapter 4