Trigonometry Table
Trigonometry
The Word 'trigonometry' is derived from
the Greek words 'tri' (meaning tree), 'gon' (meaning sides) and 'metron'
(meaning measure). In fact trigonometry is the study of relationship between
the sides and angle o the triangle.
In This chapter, we will study some ration
of the sides of a right triangle with respect to its acute angles, called
trigonometric ratios of the angle. We will restrict our discussion to acute
angle only. However, these ratios can be extended to other angles also. We will
also define the trigonometric rations for angles of measure 0o and
90o. We will calculate trigonometric ratios for some specific angles
and establish some identities involving these rations, called trigonometric
identities.
Let us take a right triangle ABC as shown
in
Here 
CAB (or, in brief,
angle A) is an acute angle. Note the position of the side BC with respect to
angle A. If faces A. we call it the side
opposite to angle A. AC is the hypotenuse of the right triangle and the side AB
is a part of A. So, we call it the side adjacent to angle A.
CAB (or, in brief,
angle A) is an acute angle. Note the position of the side BC with respect to
angle A. If faces A. we call it the side
opposite to angle A. AC is the hypotenuse of the right triangle and the side AB
is a part of A. So, we call it the side adjacent to angle A.
Note that the position of sides change
when you consider angle C in place of A.
The trigonometric ratios of the angle A
right triangle ABC are defined as follows:
tangent of
The ratio defined above are abbreviated as
sin A, cos A, tan A, cosec A, sec A and cot A respectively. Note that the
ratios cosec A, sec A and cot A are respectively, the reciprocal of the ratios
sin A, cos A and tan A.
also, observe that tan
So, the trigonometric ratios of an acute
angle in a right triangle express the relationship between the angle and the
length of its sides.
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