Question

sin(x+10deg)=cos3x then x=?

Answer 1

can you help me ?

Answer 2

u know the identity sin(90-A)=cos A ?

Answer 3

so write cos 3x as sin (90-3x)
now u have
sin(x+10) = sin (90-3x)
so
x+10 = 90-3x
can u solve this for x ?

Answer 4

Note that,
\[x + 10 + 2n \pi = 90 - 3x\]

Answer 5

i get 20 :)) thank you so much

Answer 6

yup, its 20, do u need general solution in terms of n?

Answer 7

yes yes :)

Answer 8

x+10+2nπ=90−3x
4x=80-2nπ
x=20-nπ/2

Answer 9

oh i get it. thanks but can i have 1 more question?

Answer 10

If cosA= -15/17 and A is in quadrant III, find cos 1/2A