Trigonometry: SIN, COS, TAN (with Degrees)

Excel Formulas › Math

All versionsSIN

Excel’s trig functions work in radians, not degrees — the #1 gotcha. Wrap your angle in RADIANS first, and you can compute heights, distances, and angles.

Quick formula: sine of a 30-degree angle in A2:
=SIN(RADIANS(A2))
RADIANS converts degrees to radians; SIN then returns 0.5 for 30°. DEGREES converts back.

Functions used (tap for the full reference guide):

SINRADIANS

The example

SIN(30°) = 0.5.

AB
1AngleSIN
230°0.5
390°1.0

The formula

The formula:

=SIN(RADIANS(A2)) // convert degrees first

How it works

How it works:

  1. Excel’s SIN, COS, TAN expect the angle in radians.
  2. Wrap a degree value in RADIANS(degrees) first — SIN(RADIANS(30)) = 0.5.
  3. To convert a radian result back to degrees, use DEGREES(radians).
  4. Inverse functions (ASIN, ACOS, ATAN) return radians — wrap them in DEGREES for a degree answer.

Forgetting RADIANS is the classic error. =SIN(30) computes the sine of 30 radians (about −0.99), not 30 degrees. Always convert degree inputs first, and use DEGREES on inverse results.

Try it: interactive demo

Live demo

Angle in degrees.

SIN · COS · TAN

Variations

Inverse (degrees)

Angle from a ratio:

=DEGREES(ASIN(A2))

Triangle height

opp = hyp×sin:

=hyp * SIN(RADIANS(angle))

Pi

Constant:

=PI()

Pitfalls & errors

RADIANS first. Trig functions use radians; feed degrees through RADIANS or the result is wrong.

TAN at 90°. Tangent is undefined at 90° (cos = 0) and returns a huge number.

Inverse returns radians. Wrap ASIN/ACOS/ATAN in DEGREES for a degree answer.

Practice workbook

📊
Download the free Trigonometry: SIN, COS, TAN (with Degrees) practice workbook
A trig sheet with the inverse, triangle, and pi variants, plus 4 challenges with answers. No sign-up required.

Frequently asked questions

How do I use SIN, COS, TAN with degrees in Excel?
Convert the angle first: =SIN(RADIANS(30)) returns 0.5. Excel's trig functions work in radians, not degrees.
Why is SIN(30) wrong?
It computes the sine of 30 radians, not 30 degrees. Wrap the angle in RADIANS: =SIN(RADIANS(30)).
How do I get an angle in degrees from ASIN?
Inverse functions return radians, so wrap them: =DEGREES(ASIN(value)).

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Function references: SIN · RADIANS