Question

~*~*~help please!! 10 points n medal!!~*~*~

Find the measure of angle A (image below). Round the answer to the nearest tenth.

A.
49.5°
B.
53.1°
C.
63.4°
D.
66.4°

Answer 1

hi!!

Answer 2

is it a law of sines question?
or law of cosines?

Answer 3

cosines! my computer is whack and notloading up anything

Answer 4

you got all 3 sides labelled?

Answer 5

there we go! thank you!

Answer 6

\[4^2=2^2+5^2-2\times 5\times \cos(A)\]

Answer 7

so
\[16=29-10\cos(A)\]

Answer 8

first we get \(\cos(A)\) by itself, then A

Answer 9

\[\cos(A)=\frac{13}{10}=1.3\]hmm made a mistake somewhere

Answer 10

hey sorry, i dont have a calculator, give me a minuet to look

Answer 11

oh doh

Answer 12

\[2\times2\times 5=20\]

Answer 13

no batteries ):

Answer 14

\[4^2=2^2+5^2-2\times 5\times2\times \cos(A)\]\[16=29-20\cos(A)\] so
\[\cos(A)=\frac{13}{20}=.65\]

Answer 15

lol use wolfram

Answer 16

\[A=\cos^{-1}(.65)\]

Answer 17

here
http://www.wolframalpha.com/input/?i=arccos%28.65%29

Answer 18

0.863212!

Answer 19

look at the degree answer since your answers are in degrees

Answer 20

you see it?

Answer 21

i am unsure of how to get the degree! im sorry

Answer 22

look at the link i sent
it is right there

Answer 23

49.46! thank you

Answer 24

i typed in \(\arccos(.65)\) in to wolfram, it gives the answer in radians and also in degrees

Answer 25

\[\color\magenta\heartsuit\]