Trigonometric ratios

Question 1

cosine rule for missing side

Answer 1

a² = b² + c² - 2bccosA

Question 2

cosine rule to find an angle

Answer 2

cosA = (b² + c² - a²)/(2bc)

Question 3

sine rule

Answer 3

a/sinA = b/sinB = c/sinC
or
sinA/a = sinB/b = sinC/c

Question 4

to find other solution for missing angle after using sine rule

Answer 4

sinθ = sin(180°-θ)

Question 5

area of a triangle

Answer 5

1/2 absinC

Question 6

graph of y = sinθ

Answer 6

• repeats every 360°
• crosses x axis at …-180°,0,180°,360°…
• max value of 1, min value of -1

Question 7

graph of y = cosθ

Answer 7

• repeats every 360°
• crosses x axis …-90°,90°,270°,450°….
• max value of 1, min value of -1

Question 8

graph of y = tanθ

Answer 8

• repeats every 180°
• crosses x axis at ..-180°, 0°,180°,360°..
• no min or max value
• has vertical asymptotes at x=-90°, x=90°, x=270°