Question
If 5sin²x + 3cos²x − 4 = 0, then find the value of sinx, given that 0° < x < 90°.
Solution
Given
5sin²x + 3cos²x = 4 Or,
5sin²x + 3(1 − sin²x) = 4 Or,
5sin²x + 3 − 3sin²x = 4 Or,
2sin²x = 1 Or,
sin²x = (1/2) Or,
sinx = (1/√2) (since, 0° < x < 90°)
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