• Trigonometry is derived from Greek words trigonon(three
angles) and metron (measure).
• Trigonometry is the branch of mathematics which deals
with triangles, particularly triangles in a plane where one
angle of the triangle is 900.
• Trigonometry specifically deals with relationships between the
sides and the angles of a triangle, i.e. on the trigonometric
functions, and with calculations based on these functions.
Trigonometry

History
• The origins of trigonometry can be traced to the ci-
vilizations of ancient Egypt, Mesopotamia and the
Indus Valley, more than 4000 years ago.
• Some experts believe that trigonometry
was originally invented to calculate
sundials.
• The first recorded use of trigonometry
came from the Hellinistic mathematician
Circa in 150 BC.
• Many mathemiticians like Aryabhatta, Ibn Yunus
and Al-Kashi also contributed significantly.

Right Triangle
• A triangle in which one angle is
equal to 900
is called a right angled
triangle.
• The side opposite to the right angle
is known as hypotenuse.
AC is the hypotenuse
• The other two sides are known as
legs or base and altitude
AB and AC are base and altitude
respectively

Pythagoras Theorem
• In any right triangle, the area of the square
whose side is the hypotenuse is equal to the
sum of the areas of the squares whose sides are
the two legs.
• In the figure,
AC2
= AB2
+ BC2

Trigonometric Ratios
 Sine (sin) Opposite side / Hypotenuse
 Cosine (cos) Adjacent side / Hypotenuse
 Tangent (tan) Opposite side / Adjacent side
 Cosecant (cosec) Hypotenuse / Opposite side
 Secant (sec) Hypotenuse / Adjacent side
 Cotangent (cot) Adjacent side / Opposite side

Value for Trigonometric Functions for Angle C
• Sinθ = AB/AC
• Cosθ = BC/AC
• Tanθ = AB/BC
• Cosecθ = AC/AB
• Secθ = AC/BC
• Cotθ = AC/AB

Value of Trigonometric Functions

Trigonometric Identities

Some Applications of Trigonometry
• Main use is in Construction or else this field of mathematics
can be applied in astronomy,navigation, acoustics medical
imaging, civil engineering, seismology, electrical
engineering phonetics, chemistry, number theory and many
more.

Real life Applications of Trigonometry

Conclusion
• Trigonometry is a branch of Mathematics with
several important and useful applications.
Hence, it attracts more and more research with
several theories published year after year.

Thank you!