CLASS : X - A
WHAT IS TRIGONOMETRY?
Trigonometry in basic words is the mathematics
of triangles and trigonometric functions.
The word “Trigonometry” comes from the
Greek words: ‘Trigonon’ meaning ‘triangle’ and
‘metron’ meaning a ‘measure’.
In a broader sense, trigonometry is that branch
if mathematics which deals with the
measurement of the sides and the angles of a
triangle and the problems allied with angles.
ORIGIN OF ‘SINE’
“Trigonometry is not the work of any one person or nation. Its
history spans thousands of years and has touched every major
The first use of the idea of
‘sine’ in the way we use it
today was in the work
Aryabhatiyam by Aryabhata in
Aryabhata used the word
‘ardha-jya ’ for the half chord
which came to be known as
‘jiva ’ in due course.
Later, ‘jiva ’ came to be known
as ‘sinus’ and later as ‘sine ’.
An English Professor Edmund
Gunter (1581-1626) first used
the abbreviated notation ‘sin ’ .
COSINE AND TANGENT
The origin of the terms
‘ cosine’ and ‘tangent’ was
much later. The cosine
function arose from the
need to compute the sine
of the complementary
The name cosinus
originated with Edmund
Gunter. In 1674, the
English Mathematician Sir
Jonas Moore first used the
abbreviated notation ‘cos’
THE TRIGONOMETRIC RATIOS
The Cosecant, Secant, and Cotangent
are the Reciprocals of
the Sine, Cosine,and Tangent
Note: The formulas provided
are in respect to the picture.
THE TRIGONOMETRIC VALUES
HOW TO USE
TRIGONOMETRY IN REAL
The LIFE given is elaborated as follows:
Objective : To find the angle of elevation
of a room .
Knowledge Required : 1.Trigonometric Ratios
2. Trigonometric Values (acute angles)
Materials Required : 1. A meter stick
2. A measuring tape
PERFORMING THE TASK !!
Take the meter stick and put it horizontally on
the wall to measure the length .
Now, with the help of an adult measure the
diagonal distance (hypotenuse) of your room.
Record the length in centimeters and convert
it into meters.
Take the ratio of the length of the stick to the
diagonal distance to your room.
Use the trigonometric ratios to find out the
angle of elevation of your room !!
THE MUCH AWAITED RESULT
I performed the activity mentioned and since I
took the ratio of wall to the diagonal my ratio
was as follows :
We already know that this value is equal to
Now the values I got were:
Perpendicular = 6
Hypotenuse = 12mts.
THERE’S THE ANSWER!!!
Sin A = Perpendicular
(Putting the Values)
Sin A = Sin 30
Angle of Elevation = 30o