1. ©G Dear2008 – Not to be sold/Free to use
General Mathematic
(HSC)
Further
Trigonometry
Area Formula
Stage 6 - Year 12
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©G Dear2008 – Not to be sold/Free to use

2. Find the Area using Sine (1/4)b a
Web C 1 2
Area = ab x Sin C
To use the Area Rule we need …
two sides and …
the angle between them.

3. Find the Area using Sine (2/4)
Find Area of a Doritos. 1 2
Area = ab x Sin C 1 2
= x 4 x 4
x Sin 60o
≈ 6.9 cm2
60o

4. Find the Area using Sine (3/4)
Find Area of a Doritos. 1 2
Area = bh 1 2
= x 4
x 3.6
= 7.2 cm2

5. Find the Area using Sine (4/4)
Find Area of a Doritos.
Error!!!
Why the Difference?
Error!!! 1 2
Area = ab x Sin C
a = 4,
b = 4,
c = 60o
Lower Limit =
0.5 x 3.95 x 3.95 x Sin 59.5o
≈ 6.7
Upper Limit =
0.5 x 4.05 x 4.05 x Sin 60.5o
≈ 7.1 1 2
Area = bh
b = 4,
h = 3.6
Lower Limit =
0.5 x 3.95 x 3.55
= 7.0
Upper Limit =
0.5 x 4.05 x 3.65
= 7.4
The error in both calculations overlap so both answers could be correct within the error limits.