Topic 5 Applications of Trigonometry (U2)

Question 1

What are the three trigonometric ratios?

Answer 1

1) Sin0= O/H
2) Cos0= A/H
3) Tan0= O/A

Question 2

How is the angle of elevation measured?

Answer 2

Is measured upwards from the horizontal.

Question 3

How is the angle of depression measured?

Answer 3

Is measured downwards from the horizontal.

Question 4

How are compass bearings measured?

Answer 4

Directions measured from the north or south line in either direction.

Question 5

How do you identify the compass direction?

Answer 5

• Whether the angle is measured from the north or south line in either direction.
• The size of the angle.
• Whether the angle is measured in the direction of west or east.

Question 6

How are true bearings measured?

Answer 6

Measured from north in a clockwise direction.

Question 7

how are true bearings expressed?

Answer 7

In three digits, followed by a captial T.

Question 8

What is the Sine rule for length?

Answer 8

a/ sin (A) = b/ sin (B) = c/ sin (C)

Question 9

What is the Sine rule for the angle?

Answer 9

sin (A)/ a = sin (B)/ b = sin (C)/ c

Question 10

What does A, B, C stand for in the sine rule?

Answer 10

The different angles

Question 11

What does a, b, c stand for in the sine rule?

Answer 11

They are the corressponding ooposite sides to the angles.

Question 12

When is the cosine rule used?

Answer 12

• When you know all three sides
  OR
• Two sides and the angle between them

Question 13

What is the cosine rule for length?

Answer 13

1) a(2) = b(2) + c(2) - 2bc cos (A)
2) b(2) = a(2) + c(2) - 2ac cos (B)
3) c(2) = a(2) + b(2) - 2ab cos (C)
(2) = 2 squared

Question 14

What is the cosine rule for the angle?

Answer 14

1) cos (A) = b(2) + c(2) - a(2)
———————–
2bc

2) cos (B) = a(2) + c(2) - b(2)
———————–
2ac

3) cos (AC = a(2) + b(2) - c(2)
———————–
2ab

Question 15

What formula is used when given two sides and the angle between them?

Answer 15

1) Area= 1/2 ab sin (C)
2) Area= 1/2 bc sin (A)
3) Area= 1/2 ac sin (B)