Question

how to find value of sin 18.......plz explain in detail

Answer 1

without the use of the calculator?

Answer 2

ya

Answer 3

how 2 derivate it

Answer 4

taylor expansion can estimate it for you

Answer 5

i did not get what u want to say

Answer 6

sauravshakya u may try

Answer 7

who is taylor

Answer 8

Taylor Expansion is the way of estimating and function


sinx is \[x-\frac{ x ^{3} }{ 6 }+\frac{ x ^{5} }{ 120 } -...+...\]

Answer 9

5*18=90
sin(5*18)=sin90
Let x=18 then,
sin(5x)=sin90

Answer 10

i think u r wrog somewhere

Answer 11

U can proceed from here but this will be too long but it will give u exact value.

Answer 12

we dont have a formula for sin 5 thete

Answer 13

From sin(5x)=1
u need to find the value of sinx

Answer 14

i mean to say we dont have its expansion

Answer 15

sin(5x) = sin(2x + 3x) = sin2x * cos3x + cos2x * sin3x

Answer 16

hmmmmm
that wd be 22 long

Answer 17

5x= 90
2x+3x=90
3x=90-2x
sin 3x= cos 2x
now put formula of sin 3x and cos 2x in terms of sin x only.

Answer 18

hmmmmmm this wd b an easy one

Answer 19

18=Pi/10

sin(Pi/10)=0.3090169944

F[x]\[=x-\frac{ x ^{3} }{ 6 }+\frac{ x ^{5} }{ 120 }-... \]

f[Pi/10]==0.3090170542



you decide

Answer 20

Great!

Answer 21

but when we will solve the quadrtic equation then we will get two values of sin theta

Answer 22

which one is great

Answer 23

@gohangoku58 's one

Answer 24

hmmmmmmm

Answer 25

because that gives exact value not approximate

Answer 26

hmmmmm
but two values

Answer 27

which one to select

Answer 28

u plz try it once

Answer 29

well, sin 18 lies in first quadrant so take positive value

Answer 30

hmmmmm

Answer 31

good

Answer 32

u'll get a cubic equation, with one root = 0 (can't be, rejected)
and 2 other roots.....from which u select one with positive value.....
like saura said...

Answer 33

i failed 2 use common sence

Answer 34

no not a cubic but a quadratic u try it

Answer 35

i tried it jjust now

Answer 36

sin 3x= ?

Answer 37

3sinx-4 sin cube x

Answer 38

3sinx-4 sin cube x<----cubic

Answer 39

no but sin 2 x is also there

Answer 40

*cos 2x

Answer 41

ya

Answer 42

1-2sin square x

Answer 43

then we can take sin in common

Answer 44

no u cant 1 is there

Answer 45

r u there on facebook

Answer 46

who ?

Answer 47

sorry for the personal Q

Answer 48

we both are there...

Answer 49

all of u