Page 2 - LN

o
o
sin0 = cos0 = = 1
o
o
sin30 = cos30 =
o
o
sin45 = cos45 =

o
o
sin60 = cos60 =
o
o
sin90 = = 1 cos90 =

Using the values of these two ratios we can find the other ratios also.
We can use the easy palm trick to remember these values.

Trigonometric Ratios of Some Specific Anglescan be derived geometrically.

We can determine thetrigonometric Ratios for the following five angles based on
0
0
0
0
0
our existing knowledge of pure geometry:0 ,30 ,45 ,60 and90 .

Trigonometric Ratios of 45 0
The value of tan45° can be derived exactly by theoretical approach of geometry on the
basis of a geometric property, which reveals the direct relation between opposite and

adjacent sides when angle of right angled triangle is45°.

In an isosceles Rt. angle Triangle,
Let the side be " "

1
sin45°= = =
ℎ 2 2
2