Question 993791
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Find sin2b if sin b = 7/25
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Is my understanding correct that you want to find  sin(2b)?


If so,  use the formula   sin(2b) = 2*sin(b)*cos(b).


Do you know this formula?


To complete calculations,  you need to know  cos(b)  too.

You can calculate it via  sin(b): 


cos(b) = {{{sqrt(1 - sin^2(b))}}} = {{{sqrt(1 - (7/25)^2)}}} = {{{sqrt(1-(49/625))}}} = {{{sqrt((625-49)/625)}}} = {{{sqrt(576/625)}}} = {{{24/25}}}.


Now you are ready to calculate 


sin(2b) = 2*sin(b)*cos(b) = {{{2}}}.{{{7/25}}}.{{{24/25}}} = . . . 


Please complete this calculation yourself.