Trigonometry 2

1
Trigonometry (2)

• Multiple solutions for sin and cos
• Cosine rule

2
Sin and Cos
Time allowed 5 minutes
By sketching a graph show that sin q sin(180
q) cos q cos(360 q)
3
Sine curve
4
Cosine curve
5
Easy peasy
Trigonometry is fairly straight-forward when
dealing with right angled triangles. However,
life isnt always that simple
6
The Cosine rule
B
c
a
A
b
C
a2 b2 c2 - 2bc cos A
Write this in terms of b2 and c2
7
The Cosine rule

• Examples of using the cosine rule

8
Activity 2
Time allowed Rest of lesson
Turn to page 71 of your Core 2 book and answer
questions in exercise B.