Question

If cos Θ = 4/7, what are the values of sin Θ and tan Θ?

Answer 1

@mathmale @satellite73

Answer 2

@saifoo.khan

Answer 3

@ranga

Answer 4

@ShaTay

Answer 5

I have No clue... sorry

Answer 6

Use the identity sin^2(x) + cos^2(x) = 1.
Plug in the value of cos(x) into the above identity and solve for sin(x).
Them, tan(x) = sin(x) / cos(x).

Answer 7

can't you use a calculator? in scientific mode

Answer 8

I still dont understand.

Answer 9

sin^2(x) + cos^2(x) = 1
cos(x) = 4/7
sin^2(x) + (4/7)^2 = 1
sin^2(x) + 16/49 = 1
sin^2(x) = 1 - 16/49 = (49-16)/49 = 33/49
sin(x) = sqrt(33/49) = sqrt(33) / 7.

tan(x) = sin(x) / cos(x) = sqrt(33) / 7 * 7 / 4 = sqrt(33) / 44

Answer 10

@ranga

Answer 11

You can also solve this problem by drawing a triangle, marking one of the non-ninety degree angle as x, using the definition of cos(x) to identify the adjacent and hypotenuse, etc.:

Answer 12

In my reply before last, tan(x) = sqrt(33)/4 (not 44).