Question

Find the value of cos θ if sin θ=1/2;0 degrees< θ< 90 degrees

Answer 1

cosΘ =
`(√(3) )/(2)`

Explanation:

sin²Θ + cos²Θ = 1 ( subtract sin²Θ from both sides )

cos²Θ = 1 - sin²Θ ( take square root of both sides )

cosΘ = ±
`√(1-sin^20)`

= ±
`\sqrt{1-((1)/(2))^2 }`

= ±
`\sqrt{1-(1)/(4) }`

= ±
`\sqrt{(3)/(4) }`

= ±
`(√(3) )/(2)`

since 0° < Θ < 90° , then

cosΘ =
`(√(3) )/(2)`