Question

How to find the angle if 0= 3cosx - 4sinx??

Answer 1

use complementary angle method

Answer 2

I kind of forgat how to use it

Answer 3

i'm stretching my memory as well....

Answer 4

i think you can use
Rcos (x + a) = Rcosxcosa - Rsinxsina
now compare this with
3cosx - 4sinx = 0
and compare coefficients

hmm... maybe there an easier way though..
maybe you can use sinx = square root(1 - cos^2 x)

Answer 5

4 square root(1 - cos^2x) = 3 cos x
16(1 - cos^2 x) = 9cos^2 x
solve for x

Answer 6

that gives cos^2x = 16/25
cos x = 4/5 or -4/5 right?

Answer 7

Yeah right my textbook says the same answer,but one question how did you get the 16

Answer 8

i squared ;4 square root(1 - cos^2x)'

Answer 9

squaring both sides

Answer 10

Oh okay now it makes sense to me thanks for your help

Answer 11

yw

Answer 12

thats ne finished tonight - i must drink some cwrw

Answer 13

later saria

Answer 14

Yeah right ....later