The angles by which trigonometric functions can be represented are called as trigonometry angles. The important angles of trigonometry are 0Â°, 30Â°, 45Â°, 60Â°, 90Â°. These are the standard angles of trigonometric ratios, such as sin, cos, tan, sec, cosec, and cot. Each of these angles has different values with different trig functions.

**Table of Contents:**

The two rays that have the same beginning point that forms the figure called an angle. The same beginning point is called the vertex and those two rays are called the sides of the angle which is also called as legs. Let us discuss in detail all the angles.

## What are Trigonometry Angles?

**Trigonometry angles** are the angles given by the ratios of the trigonometric functions. Trigonometry deals with the study of the relationship between angles and the sides of a triangle. The angle value ranges from 0-360 degrees. The important angles in trigonometry are **0Â°, 30Â°, 45Â°, 60Â°, 90Â°, 180Â°, 270Â° and 360Â°.** And the important six trigonometric ratios or functions are sine, cosine, tangent, cosecant, secant and cotangent.

Before discussing the trig angles, let us have a look at the definition of angle, and its related terminologies. Trigonometry is an important topic for Class 10, 11 and 12. Hence, it is required for students to learn the concept in a detailed manner to excel in the exam. Learn all the related trigonometric topics here with us at BYJU’S.

### Radians and Degrees

The two common measurements used for determining angles are degree and radians. The most familiar unit of measurement of an angle is a degree. Consider, a circle is divided into 360 equal parts, where we can get the right angle with 90^{0}. Further, each degree is subdivided into 60 minutes and each minute is again subdivided into 60 seconds. The symbols used for degrees, minutes and seconds are Â°, ‘ and ” respectively. Minutes and seconds are also stated as arcminutes and arcseconds.

Beyond practical geometry in mathematics, angles are also used to measure in radians. The circle with the angle of 1 radian determines an arc with the length of the radius. Because the length of the full circle is 2Ï€r. Alternatively, we can say that the circle contains 2Ï€ radians. The subdivision of radians is also written in decimal forms.

Because **2 Ï€ = 360**Â°, the following conversion formulas has to be applied.

- r radÂ â†’ [ 360.r/2
**Ï€**]Â° - gÂ°â†’ [ 2
**Ï€**.g/360] rad

## Trigonometry Table of all Angles (0 to 360)

Here there are some special angles provided with the trigonometric numbers. To simplify the way of calculation of the trigonometric numbers at various angles, reference angles are used which are derived from the primary trigonometric functions. We can derive values in degrees like 0Â°, 30Â°, 45Â°, 60Â°, 90Â°, 180Â°, 270Â°Â and 360Â°. The trigonometric tableÂ is given below, which defines all the values of trigonometric ratios.

Angle (in Degrees) |
0Â° |
30Â° |
45Â° |
60Â° |
90Â° |
180Â° |
270Â° |
360Â° |

Angle (in Radians) |
0 |
Ï€/6 |
Ï€/4 |
Ï€/3 |
Ï€/2 |
Ï€ |
3Ï€/2 |
2Ï€ |

Sin |
0 | 1/2 | 1/âˆš2 | âˆš3/2 | 1 | 0 | -1 | 0 |

Cos |
1 | âˆš3/2 | 1/âˆš2 | 1/2 | 0 | -1 | 0 | 1 |

Tan |
0 | 1/âˆš3 | 1 | âˆš3 | âˆž | 0 | âˆž | 0 |

Cot |
âˆž | âˆš3 | 1 | 1/âˆš3 | 0 | âˆž | 1 | âˆž |

Sec |
1 | 2/âˆš3 | âˆš2 | 2 | âˆž | -1 | âˆž | 1 |

Cosec |
âˆž | 2 | âˆš2 | 2/âˆš3 | 1 | âˆž | -1 | âˆž |

### Important Angles of Trigonometry

The special angles used in trigonometry are 0Â°, 30Â°, 45Â°, 60Â° and 90Â°. These are the common angles which are used while performing computations of trigonometric problems. Hence, it is suggested for students to memorise the values of trigonometric ratios (sine, cosine and tangent) for these angles, to do quick calculations.

### Positive and Negative Angles

The angles could be positive or negative in nature. If the angle is formed in a counterclockwise direction from the start point in an x-y plane, then it is positive and if the angle is formed in a clockwise direction from the start point then it is a negative angle.

### Angles More Than 360Â°

Once a complete cycle is done in an x-y plane, that means if we start the cycle from 0Â° and ends at 360Â°, a full circle is made. One full cycle also resembles a unit circle. After that, if we still keep going then the angles are greater than 360Â°. Now beyond 360Â° at each quadrant, you will get the angles, such as 450Â°, 540Â°, 630Â°, 720Â°, and so on. At 720Â° two cycles are completed and with respect to radians, it is measured as 4Ï€. Similarly, the value of radians at each cycle is increased as n x 2Ï€. So we can show this in a table as:

Number of Cycle |
Angle (n x 360Â°) |
Radians (n x 2Ï€) |

1 | 360Â° | 2Ï€ |

2 | 720Â° | 4Ï€ |

3 | 1080Â° | 6Ï€ |

4 | 1440Â° | 8Ï€ |

## Trigonometry Angles Formulas

The formulas for trigonometry angles are based on the four quadrants of a unit circle. See the figure below to understand.

### Supplementary angles ( = sum is Ï€)

- Sin ( Ï€ – Î± ) = sin Î±
- Cos (Ï€ – Î± ) = – cos Î±
- Tan (Ï€ – Î± ) = – tan Î±
- Cot (Ï€ – Î±) = – cot Î±

### Anti-supplementary Angles (= difference is Ï€)

- Sin ( Ï€ + Î± ) = – sin Î±
- Cos (Ï€ + Î± ) = – cos Î±
- Tan (Ï€ + Î± ) = tan Î±
- Cot (Ï€ + Î± ) = cot Î±

### Opposite Angles ( = sum is 2Ï€)

- Sin ( 2Ï€ – Î± ) = – sin Î±
- Cos (2Ï€ – Î± ) = cos Î±
- Tan (2Ï€ – Î± ) = -tan Î±
- Cot (2Ï€ – Î± ) = – cot Î±

### Complementary Angles (= sum is Ï€/2)

- Sin ( Ï€/2 – Î± ) = cos Î±
- Cos (Ï€/2 – Î± ) = sin Î±
- Tan (Ï€/2 – Î± ) = cot Î±
- Cot (Ï€/2 – Î± ) = tan Î±

Also, see:Â Trigonometry Formulas

## Examples

**Question 1:Â Find the value of sin 60 – cos 30.**

**Solution: **

The value of sin 60 =Â âˆš3/2Â

Value of cos 30 =Â âˆš3/2

Hence, sin 60 – cos 30 =Â âˆš3/2 –Â âˆš3/2 = 0

**Question 2:Â Evaluate the value of 3sin 30 + tan 45**

**Solution: **

Value of sin 30 = 1/2

Value of tan 45 = 1

By putting the values we get;

=3(1/2)+1

=3/2+1

=5/2

**Question 3:Â If sin 3A = cos (A-26Â°), where 3A is an acute angle, find the value of A.**

**Solution:**

Given that, sin 3A = cos (A-26Â°) â€¦.(1)

Since, sin 3A = cos (90Â°Â – 3A), we can write (1) as:

cos(90Â°- 3A)= cos (A- 26Â°)

Since, 90Â°-3A = A – 26Â°

Therefore,

90Â°Â + 26Â°Â = 3A + A

4 A = 116Â°

A = 116Â°Â / 4 = 29Â°

Therefore, the value of A is 29Â°.

**Question 4:Â IfÂ Î± = 60Â° and Î² = 30Â°, prove that sin (Î± – Î²) = sinÂ Î± cosÂ Î² – cosÂ Î± sinÂ Î².**

**Solution: **

L.H.S. = sin (Î± – Î²)

= sin (60Â° – 30Â°)

= sin 30Â°

= Â½

R.H.S. = sinÂ Î± cosÂ Î² – cosÂ Î± sinÂ Î²

= sin 60Â° cos 30Â° – cos 60Â° sin 30Â°

= (âˆš3/2)Ã—(âˆš3/2)âˆ’(1/2)Ã—(1/2)

= Â¾ – Â¼

= 2/4

= Â½

Hence, L.H.S. = R.H.S. (Proved)

**Question 5:Â IfÂ Î± = 30Â°, verify that 3 sinÂ Î± – 4 sin ^{3}Â Î± = sin 3Î±.**

**Solution:Â **

L.H.S = 3 sinÂ Î± – 4 sin^{3}Â Î±

= 3 sin 30Â° â€“ 4. sin^{3} 30Â°

= 3 âˆ™ (1/2) – 4 âˆ™ (1/2)^{3}

= 3/2 â€“ 4 âˆ™ 1/8

= 3/2 â€“ Â½

= 1

R.H.S. = sin 3Î±

= sin 3 âˆ™ 30Â°

= sin 90Â°

= 1

Hence, L.H.S. = R.H.S. (Proved)

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