Sine and cosine — a.k.a., sin(θ) and cos(θ) — are functions revealing the shape of a right triangle. Looking out from a vertex with angle θ, sin(θ) is the ratio of the opposite side to the hypotenuse , while cos(θ) is the ratio of the adjacent side to the hypotenuse .

## What are the actual word for sine and cosine?

Sine and cosine — a.k.a., sin(θ) and cos(θ) — are functions revealing the shape of a right triangle. Looking out from a vertex with angle θ, sin(θ) is the ratio of the opposite side to the hypotenuse , while cos(θ) is the ratio of the adjacent side to the hypotenuse .

## How do you remember the sine and cosine rule?

The sine, cosine, and tangent ratios in a right triangle can be remembered by representing them as strings of letters, for instance SOH-CAH-TOA in English: Sine = Opposite ÷ Hypotenuse. Cosine = Adjacent ÷ Hypotenuse.

Why is it called sine and cosine?

In trigonometry, the name “sine” comes through Latin from a Sanskrit word meaning “chord”. In the picture of a unit circle below, AB has length sinθ and this is half a chord of the circle. The co-functions are functions of complementary angles: cosθ = sin(π/2 − θ), cotθ = tan(π/2 − θ), and cscθ = sec(π/2 − θ).

### Is sine and cosine the same?

The sine of any acute angle is equal to the cosine of its complement. The cosine of any acute angle is equal to the sine of its complement. of any acute angle equals its cofunction of the angle’s complement.

### Why cosine is called cosine?

The word sine (Latin sinus) comes from a Latin mistranslation by Robert of Chester of the Arabic jiba, itself a transliteration of the Sanskrit word for half of a chord, jya-ardha. The word cosine derives from a contraction of the medieval Latin complementi sinus.

Who is called Father of trigonometry?

The first known table of chords was produced by the Greek mathematician Hipparchus in about 140 BC. Although these tables have not survived, it is claimed that twelve books of tables of chords were written by Hipparchus. This makes Hipparchus the founder of trigonometry.

#### When can you use cosine rule?

You can usually use the cosine rule when you are given two sides and the included angle (SAS) or when you are given three sides and want to work out an angle (SSS). In order to use the sine rule, you need to know either two angles and a side (ASA) or two sides and a non-included angle (SSA).

#### How does the cosine rule work?

The cosine rule, also known as the law of cosines, relates all 3 sides of a triangle with an angle of a triangle. It is most useful for solving for missing information in a triangle. For example, if all three sides of the triangle are known, the cosine rule allows one to find any of the angle measures.

Why do we need sine and cosine?

It can help us better understand the connections between the sides and angles of rectangles. Sine, cosine, and tangent are important to the study of right triangles. Have you ever seen this type of triangle? If so, you know that one of its three angles is always 90° (a right angle).

## What are trig functions used for in real life?

Trigonometry is used to set directions such as the north south east west, it tells you what direction to take with the compass to get on a straight direction. It is used in navigation in order to pinpoint a location. It is also used to find the distance of the shore from a point in the sea.

## What is the relationship between sine and cosine graphs?

Relationship between Sine and Cosine graphs The graph of sine has the same shape as the graph of cosine. Indeed, the graph of sine can be obtained by translating the graph of cosine by ( 4 n + 1 ) π 2 \frac{(4n+1)\pi}{2} 2(4n+1)π​ units along the positive x x x-axis ( n n n is an integer).

Are sin and cos inverse functions?

Inverse functions are also called as Arc Functions because they give the length of the arc for a given value of trigonometric functions. They are usually written as arcsin(x), arccos(x), arctan(x), etc….What is Arccosine?

Function Inverse Trig Function
sine arcsine
cosine arccosine
tangent arctangent
secant arcsecant