Pre-Calculus 11 - Ms. Skehills' Classroom€¦ · Web view2.4 – The Cosine Law Review: y x 1 When...
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Pre-Calculus 11 2.4 – The Cosine Law Review: When radius = 1 x = cos and y = sin The Cosine Law relates the sides to one of the opposite angles in any triangle. When do we use the cosine law? Ex 1: Find side a Ex 2: Find side c y x 1 a 2 =b 2 + c 2 −2 bc cos a C B 41 5 6 a 4 3 70 Test: a) cos 2 30 + sin 2 30 b) cos 2 68 + sin 2 68 c) cos 2 45 + sin 2 45 What can you generalize for cos 2 A + sin 2 A ? A C C B b c a
Transcript of Pre-Calculus 11 - Ms. Skehills' Classroom€¦ · Web view2.4 – The Cosine Law Review: y x 1 When...
Pre-Calculus 11
2.4 – The Cosine LawReview:
When radius = 1x = cos and y = sin
The Cosine Law relates the sides to one of the opposite angles in any triangle.
When do we use the cosine law?
Ex 1: Find side a
Ex 2: Find side c
1
x
y
a2=b2+c2−2bccos a
a
6
5
41B
C
70 34
Test: a) cos2 30 + sin2 30
b) cos2 68 + sin2 68
c) cos2 45 + sin2 45
What can you generalize for cos2 A + sin2 A ? Why?
a
c
b
B
C
A
C
A
B
c
Ex 4: Calculate A and C.
Note: When solving triangles
SAS Cosine LawSSS Cosine LawASS Sine Law*2 angles, one side Sine Law
Ex 5: Solve for all sides and angles
* Homework: Pg. 119 # 1 – 2 (a, c), 3, 4a, 5, 6, 10
A
B
C5
34
A
B
C
5 63
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