The exact value of sinθ in simplest form, with cosθ = 2/5 and θ in Quadrant IV, is -√21/5.
To find the exact value of sinθ, we can use the Pythagorean identity: sin²θ + cos²θ = 1. Since we know the value of cosθ, we can substitute it into the equation and solve for sinθ.
Given that cosθ = 2/5 and θ is in Quadrant IV, we know that the cosine is positive in Quadrant IV, and the sine is negative. Let's proceed with the calculations:
sin²θ + cos²θ = 1
sin²θ + (2/5)² = 1 (Substituting cosθ = 2/5)
sin²θ + 4/25 = 1 (Simplifying)
sin²θ = 1 - 4/25 (Subtracting 4/25 from both sides)
sin²θ = 21/25 (Simplifying)
Taking the square root of both sides, considering that sinθ is negative in Quadrant IV:
sinθ = -√(21/25)
Since we want to express the answer in simplest form, we can simplify the radical:
sinθ = -√21/√25
The square root of 25 is 5, so we can simplify further:
sinθ = -√21/5
Therefore, the exact value of sinθ in simplest form, given that cosθ = 2/5 and θ is in Quadrant IV, is -√21/5.
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