# Definition of tangent in English:

## tangent

Pronunciation: /ˈtan(d)ʒ(ə)nt/

## noun

1A straight line or plane that touches a curve or curved surface at a point, but if extended does not cross it at that point.
Example sentences
• He noticed that he could draw three straight lines, or tangents, that each touched all three circles.
• Since normals to a straight line never intersect and tangents coincide with the curve, evolutes, involutes and pedal curves are not too interesting.
• One of his most important results explains how the 28 double tangents of the plane quadric are related to the 27 straight lines of the cubic surface.
2A completely different line of thought or action: Loretta’s mind went off at a tangent
More example sentences
• Look at that, we started with the opening credits and I went off on a tangent.
• Otherwise, people will start going off on different tangents, and you can't have that.
• Thankfully, he went off on a different tangent.
3 Mathematics The trigonometric function that is equal to the ratio of the sides (other than the hypotenuse) opposite and adjacent to an angle in a right-angled triangle.
Example sentences
• The first tabulates logarithms of the sine, cosine, tangent and cotangent functions at 1 intervals and shows how to solve triangles using logarithmic functions.
• The proof needs another formula about tangents of angles that we have not covered on the Pi and the Fibonacci Numbers page.
• If the tangent of an angle is a/b then the cotangent of that angle is b/a.

(Of a line or plane) touching, but not intersecting, a curve or curved surface: this curve is tangent to the average cost curve
More example sentences
• Smooth infinitesimal analysis embodies a concept of intensive magnitude in the form of infinitesimal tangent vectors to curves.
• Construct two tangent circles 1 and 2 and the line L through their centers.
• The Kummer surface has 16 isolated conical double points and 16 singular tangent planes and was published in 1864.

## Derivatives

#### tangency

Pronunciation: /ˈtan(d)ʒ(ə)nsi/
noun
Example sentences
• Depending on the geometry type, you can preserve projection, plane, position, tangency, curvature, and any valid combination of these characteristics.
• For complementary resources, this combination is also the point of tangency between an isocline and the constraint curve.
• Two tangents of a parabola are divided into segments of like proportion by a third and this third is divided in the same proportion by its point of tangency.

## Origin

Late 16th century (in sense 3 of the noun and as an adjective): from Latin tangent- 'touching', from the verb tangere.

More
• tact from mid 17th century:

Tact in early examples referred to the sense of touch. It comes from Latin tactus ‘touch, sense of touch’, from tangere ‘to touch’. The word developed a notion of ‘sensitivity’ and in the late 18th century gained its modern sense ‘delicacy in dealing with others’. The Latin source also gave the English word tactile which in the early 17th century meant ‘perceptible by touch’, and tangible (late 16th century). Tangent (late 16th century), first used in geometry to mean ‘touching’, is also from tangere.

## Words that rhyme with tangent

cotangent, plangent

## For editors and proofreaders

Line breaks: tan|gent

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## Related Words

### More words in this category

angle 1 arrowhead cardioid decagon dodecahedron