radian
Circle's natural angle
A radian is a unit of angular measure used in mathematics and science.
One radian is the angle formed when the arc length equals the radius of the circle—about 57.3 degrees.
A full circle contains 2π radians.
Radians simplify many formulas in trigonometry and calculus: Convert 90 degrees to radians.
Unit of measurement
- arcCurved line segment
- rotationTurning on an axis
- turnRotational movement
- angleGeometric measure of rotation
steradian · revolution · cycle · subtend · magnitude · protractor · compass · conversion
Opposite over hypotenuse
- cosineRatio in triangle math
- tangentLine touching curve once
- secantTrig ratio, 1/cos
- cotangentTangent reciprocal function
cosecant · unit circle · periodic · oscillation · waveform · frequency · phase · amplitude
Circle's outer measurement
- arc lengthCurved segment's measure
- diameterDistance across through center
- sectorDistinct division of whole
- central angleAngle at circle's midpoint
subtended · revolution · sweep · chord · inscribed · perimeter · center · orbit
Fixed, unvarying quantity
- irrationalLacking sound judgment
- transcendentalBeyond ordinary experience
- ratioComparative numerical relation
- formulaFixed method or notation
degree
Unit of measurement
angle · steradian · revolution · cycle · subtend · magnitude · protractor · compass · conversion · unit
sine
Opposite over hypotenuse
cotangent · cosecant · unit circle · periodic · oscillation · waveform · frequency · phase · amplitude · harmonic
circumference
Circle's outer measurement
- arc lengthCurved segment's measure
- diameterDistance across through center
- sectorDistinct division of whole
central angle · subtended · revolution · sweep · chord · inscribed · perimeter · center · orbit
constant
Fixed, unvarying quantity
- irrationalLacking sound judgment
- transcendentalBeyond ordinary experience
- ratioComparative numerical relation
- anglesacute angle, angle, obtuse angle, right angle, straight angle
- circlesfull circle, circle, circumference, pie chart, semicircle
- unitsunit, angstrom, yard, meter, base units
- trigonometrysine, cosine, tangent, secant, cosecant
- SI Unitsampere, candela, kilogram, metre, second
- Navigation Unitsnautical mile, knot, fathom, bearing, heading
- radiant heatingSurface-emitted thermal energy
- background radiationResidual energy from early universe
- X-ray radiationShort-wavelength electromagnetic emission
- radiant heatersDevices emitting warming electromagnetic waves
- blast radiusArea affected by explosion
- nuclear radiationEnergy from atomic decay
radiant, radiate, radiance, radiation, radiator, radial, radius, radiating, radiated