Question

In ABC, C is a right angle, what is the measure of x?



A. 22.4°

B. 67.6°

C. 20.9°

D. 69.1°

Answer 1

can you give the trig ratio involving the two given sides and the angle x for me?

Answer 2

i'm sorry ,i don't understand?

Answer 3

you have a right triangle and the length of 1 leg and the hypotenuse...
notice angle A (x) is the angle between the two given sides...

what trigonometric ratio involves those two given sides with the angle x ???

Answer 4

ever heard of SOH-CAH-TOA ???

Answer 5

8/21?

Answer 6

and no i've never heard of it...

Answer 7

SOH: Sine is Opposite over Hypoteuse
CAH: Cosine is Adjacent over Hypotenuse
TOA: Tangent is Opposite over Adjacent

it is just a mnemonic to help remember the trig ratios...

Answer 8

so in your case, "x" is the angle between the two given sides so the trig ratio is:

\(\large cosx=\frac{8}{21} \)

that' the equation that needs to be solved for x.

Answer 9

do u know what to do from here?

Answer 10

well when i divide 8/21 i get 0.380... so how would i go about solving from there?

Answer 11

do you know about inverse trig functions?

Answer 12

no , sorry i've been sick with the flu causing me to miss my lessons so i've gotten very far behind.

Answer 13

to find x in the equation cos x = 8/21, you need to take the inverse cosine of 8/21 to get the value of x:

from \(\large cosx=\frac{8}{21} \) you can solve for x by
\(\large x=cos^{-1}(\frac{8}{21}) \)

Answer 14

just make sure your calculator is in DEGREE MODE when calculating this...

Answer 15

here it is using wolfram calculator... use the degree answer given...
http://www.wolframalpha.com/input/?i=inverse+cosine+%288%2F21%29

Answer 16

thank you very much!