Topic 5 - Trigonometry

Question 1

What is the sine rule?

Answer 1

a/sinA = b/sinB = c/sinC

Question 2

What is the cosine rule?

Answer 2

a^2=b^2+c^2 - 2abcosC

Question 3

What is the formula for the area of a triangle?

Answer 3

1/2 absinC

Question 4

What is the formula for secx?

Answer 4

1/cosx

Question 5

What is the formula for cosecx?

Answer 5

1/sinx

Question 6

How can you find tanx given sinx and cosx?

Answer 6

tanx=sinx/cosx

Question 7

What is the formula for cotx?

Answer 7

1/tanx

Question 8

What is a trigonometry rule relating to sin2(x) + cos2(x)

Answer 8

sin^2(x)+cos^2(x)=1

Question 9

What is a trigonometry rule relating to sec^2(x)?

Answer 9

sec^2(x)=1+tan^2(x)

Question 10

What is a trigonometry rule relating to cosec^2(x)?

Answer 10

cosec^2(x)=1+cot^2(x)

Question 11

What is a trigonometry rule relating to sin(A+/-B)?

Answer 11

sin(A+/-B) = sinAcosB +/- cosAsinB

Question 12

What is a trigonometry rule relating to cos(A+/-B)?

Answer 12

cos(A+/-B) = cosAcosB -/+ sinAsinB

Question 13

What is a trigonometry rule relating to tan(A+/-B)?

Answer 13

tan(A+/-B) = (tanA +/- tanB)/

1 +/- tanAtanB

Question 14

What is a trigonometry rule relating to cos2x?

Answer 14

cos2x = cos^2(x) - sin^2(x)

= 2cos^2(x) - 1 = 1 - 2sin^2(x)

Question 15

What is a trigonometry rule relating to sin2x?

Answer 15

sin2x = 2sinxcosx

Question 16

What is a trigonometry rule relating to tan2x?

Answer 16

tan2x = 2tanx/

1 - tan^2(x)