Question

EXPRESS EACH OF THE FOLLOWING AS A SUM OR DIFFERENCE :
1. cos 61 degree * sin 39 degree
2. sin 36 degree * sin 24 degree

Answer 1

helllo this is your anawer

Answer 2

Step-by-step explanation:

What is the value of sin39° ? How do I find this value without using a calculator?

I don't feel that there is any feasible solution for it. You can only get accurate answer from a calculator which works on finite analysis of the sine curve. However, there is a way of finding the values of sine function for an angle which is not a standard angle like 30,45,60 or 90 degrees.

You can interpolate between any two known values because the shape of the sine curve is somewhat straight between certain values. Hence, it can be interpolated using straight line formula.

So, we know sin45°= 1/√2 and sin 30°=1/2

hence, using straight line formula,

y-y' =((y'’-y')/(x''-x'))*(x-x')

sin 39°=((sin

Hi Tanmoy,

if you really interested to calculate sin 39(degree) then

procedure like this

you know the value of sin 18(degree)

so apply half angle formula you get sin 9(degree) after some calculation.

sin(18)=2 sin (9degree) * cos 9(degree)

changes cosine in sine term then solve..

after than apply this

sin((30 + 9)degree) = sin((30)degree)*cos((9)degree) + cos((30)degree)*sin((9)degree)

i hope you get the idea that how to calculate the sin(39 degree).