Question

@Michele_Laino

Answer 1

Do I use sine or cosine?

Answer 2

we can write this formula:
\[11 = 21\cos x\]
therefore, we have:
\[\cos x = \frac{{11}}{{21}} = ...?\]

Answer 3

0.865

Answer 4

This is how I entered it in my calculator cos(11/21)=0.8659

Answer 5

I got this value:
\(11/21=0.524\) then we have to compute the inverse function of cosine:
\[x = \arccos \left( {0.524} \right) = ...?\]

Answer 6

or, using an equivalent notation:
\[x = {\cos ^{ - 1}}\left( {0.524} \right) = ...?\]

Answer 7

you can use WIndows calculator for example

Answer 8

1.019

Answer 9

I'm using my TI-84 plus... It's in radians mode

Answer 10

please use it in "deg" mode

Answer 11

Alright :) I got 58.3

Answer 12

yes! so what is the right option?

Answer 13

Option B.. Since, the value can't be rounded.

Answer 14

that's right!