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Math function
COS
Returns the cosine of an angle in radians.
Rarely usedDifficulty 1100 · ProficientUsage rank #247 of 520
When to use it
Cosine of an angle in radians. Horizontal components, phase-shifted waves, and the dot-product angle formula.
The shape of it
- Syntax
=COS(number)
Worked examples
Zero
=COS(0) → 1
Maximum at zero.
Half a turn
=COS(PI()) → -1
Half a turn.
From degrees
=COS(RADIANS(60)) → 0.5
From degrees.
Worth knowing
- Horizontal component: magnitude*COS(angle).
- COS and SIN are 90° apart: COS(x) = SIN(x+PI()/2).
- ACOS inverts it.
Where it goes wrong
- Degrees must be converted to radians first.
- COS(PI()/2) returns 6.1E-17, not 0; ROUND if you test for zero.
Related
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