EXAMPLE 4

Find the area of the triangle shown in the fig.41

Solution

In triangle ABC, ÐA = 180⁰ - ( Ð B + Ð C)

\ ÐA = 180⁰ - (117⁰ + 28⁰) = 35⁰

using the formula

EXAMPLE 5

In triangle PQR, Ð Q = Ð R = 70⁰. QR = 20 cms. Find its area .

Solution

In triangle PQR, Ð P = 180⁰ - ( Ð Q + Ð R)

\ Ð P = 180 Ð - (70⁰ + 70⁰) = 40⁰

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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