Question

solve equation in the interval from 0 to 2pi.
7 cos 2t =3

Answer 1

corrections 7 cos 2t=3

Answer 2

arccos 3/7 - your calculator will give u the value of t in first quadrant
the other value is in 4th quadrant

Answer 3

what does arccos mean

Answer 4

am I setting calculator in rad. or degrees

Answer 5

oh - then find angle whose cos is 3/7 0 calculator will give you value of 2t in first quadrant

Answer 6

right - set to rad arccos means the angle whose cos is given value
or - on calculator button this might be cos -1

Answer 7

cos 3/7= .91 now what

Answer 8

how do I get the other value

Answer 9

you need cos-1 not cos

check again : i make it 1.128 rad

Answer 10

ok that is 1.099??

Answer 11

1/cos(3/7) right?

Answer 12

and how do you know I need cos-1 and not cos?

Answer 13

no - the cosine of the angle 2t = 3/7
you need to find the angle whose cosine is 3/7
first find 3 / 7 on ur calculator

then you need to press the cos-1 (or arccos) button

Answer 14

do I just press cos then -1

Answer 15

cos-1 does not mean 1 / cos in this context

Answer 16

no there is probably a button marked cos but you first press the shift key then cos button to get value of the angle

Answer 17

cos-1 notation is a bit confusing - in Europe they use arccos which makes more sense

Answer 18

cos (3/7)=.91. Do I press shift key before entering cos (3/7)? don't know the shift key

Answer 19

I haven't done any problems with cos-1

Answer 20

calculators vary
you either press shift cos (3/7)

or (3/7) shift cos

Answer 21

the correct value is 1.127 (to 3 dec places)

Answer 22

sorry 1.128

Answer 23

its a bit hard to explain without seeing your calculator....