if sinA=-7/25 where 180

Question

if sinA=-7/25 where 180<A<270, find tan(A/2)

i just want to make sure that my answer is correct.. -1/7 ?

hartnn · Answer

what A did u get ?

anonymous · Answer

-16.26020471

and then i substitute it to tan(A/2) which gave me -1/7
but i doubted my answer because of the 180<A<270, how will i do this? is my answer correct??

hartnn · Answer

-16.2 is in 4th quadrant, not in 3rd

anonymous · Answer

ow.. so there is another value for A? which will be in the 3rd quadrant?

hartnn · Answer

yes.

hartnn · Answer

which i m trying to find

anonymous · Answer

did you got it?? how??

hartnn · Answer

sin(180-(-16.2))=sin(-16.2)=sin(196.2)
so A=196.2

hartnn · Answer

got that^ ?

anonymous · Answer

waa!!.. -7 is the answer??
how did u arrived with the sin(180-(-16.2))?

hartnn · Answer

because sin(180-B)=sin B
so i had sin(-16.2)=-7/25
i wanted to bring the angle in 3rd quadrant, so i used sin(180-B)=sin B

anonymous · Answer

but when 270<A<360, is my answer correct?? -1/7?

hartnn · Answer

yup.
4th quadrant.

anonymous · Answer

owh.. thanks again..! :)) i have more questions.. i'll just post it :))