Question

If sin θ = 2 over 7 and tan θ > 0, what is the value of cos θ?

Answer 1

Sin θ = 2 / 7
tan θ > 0
cos θ = ?

sin θ = opposite / hypotenuse
tan θ = opposite / adjacent
cos θ = adjacent / hypotenuse

short leg = opposite = 2
hypotenuse = 7
long leg = adjacent = ?

adjacent = √(7² - 2²)
adjacent = √(49 - 4)
adjacent = √45
adjacent = √9 * 5
adjacent = 3 √5

cos θ = adjacent / hypotenuse
cos θ = 3√5 / 7