JAMB - Mathematics (1994 - No. 31)

What is the value of sin(-690)?
\(\frac{\sqrt{3}}{2}\)
-\(\frac{\sqrt{3}}{2}\)
\(\frac{-1}{2}\)
\(\frac{1}{2}\)

Explanation

Sin(-690o) = Sin(-360 -3300

sin - 360 = sin 0

∴ sin(-690o) = sin(330o)

Negative angles are measured in clockwise direction

The acute angle equivalent of sin(-330o) = sin(30o)

sin(-330o) = sin(30o)

= \(\frac{1}{2}\)

= 0.5

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