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Question
If cos θ = `24/25`, then sin θ = ?
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Solution
cos θ = `24/25` ......[Given]
We know that,
sin2θ + cos2θ = 1
∴ `sin^2theta + (24/25)^2` = 1
∴ `sin^2theta + 576/625` = 1
∴ sin2θ = `1 - 576/625`
∴ sin2θ = `(625 - 576)/625`
∴ sin2θ = `49/625`
∴ sin θ = `7/25` ......[Taking square root of both sides]
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Solution:
In Δ ABC, ∠ABC = 90°, ∠C = θ°
AB2 + BC2 = `square` .....(Pythagoras theorem)
Divide both sides by AC2
`"AB"^2/"AC"^2 + "BC"^2/"AC"^2 = "AC"^2/"AC"^2`
∴ `("AB"^2/"AC"^2) + ("BC"^2/"AC"^2) = 1`
But `"AB"/"AC" = square and "BC"/"AC" = square`
∴ `sin^2 theta + cos^2 theta = square`
