Page 33 - CITS - WCS - Mechanical

WORKSHOP CALCULATION - CITS

EXERCISE 6 : Trigonometry

Concept of angles, grades and radians and their conversions, measurement of angles in degrees.
Trigonometrically ratios and their relations. Review of ratios of some standard angles (0, 30,45,60,90
degrees), Height & Distances, Simple problems.
Trigonometry is a most significant topic of math’s that will help us to understand the relationships between the
angles and sides of triangles and Trigonometry formulas give us the facility to solve complex problems involving
angles, distances, and other geometric conception. This article on Trigonometry Formulas includes a trigonometry
table with function values and all trigonometry formulas which is very useful in board exams.

Trigonometry - Measurement of angles
Introduction:
Trigonometry is the branch of mathematics which deals with the study of measurement and relationship of the
three sides and three angles of a triangle.
Units:
Measurement of Angles
There are three systems of measuring the angle:

i Sexagesimal System
This is called British System. In this system, one right angle is divided into 90 equal parts which are called
degrees. Each part is divided into 60 parts which are called minutes. Each minute is divided into 60 parts which
are called seconds. The parts so divided respectively are called:
One degree (1°), one minute (1’) and one second (1”)
It means 1 right angle = 90° (90 degrees)
1 degree (1°) = 60’ (60 minutes)

1 minute (1’) = 60” (60 seconds)
In Trigonometry, mostly this system is used.
ii Centesimal System
This is called French System. In this system, the right angle is divided into 100 equal parts which are called
grades. Each grade is divided into 100 minutes and each minute is divided into 100 seconds.
Parts so divided are respectively called:
One grade (1 g), one minute (1’ ), one second (1”).
It means 1 right angle = 100 grades (100g)

1 grade (1 g) = 100 minutes (100’)
1 minute (1’) = 100 seconds (100”)
90° = 100g (because each is a right angle)

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