Question

In triangle ABC, what is the measure of A if a = 11, b = 13, and c = 7?

57.79°

49.62°

38.17°

32.21°

Answer 1

use the law of cosines...

\[\cos(A) = \frac{c^2 + b^2 - a^2}{2bc}\]

Answer 2

ight

Answer 3

7^2+13^2-11^2/2(13)(7)?

Answer 4

that will give the cos(A)

to find A

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

Answer 5

so 182

Answer 6

97/182?

Answer 7

no... use brackets

(b^2 + c^2-a^2)/(2bc)

Answer 8

ok... then find the answer

Answer 9

oops angle

Answer 10

I multiplied the bottom and got 182

Answer 11

ok... so on the calculator is shift cos then 97/182

Answer 12

and then I get 53.3%

Answer 13

ok

Answer 14

well that's not correct...

does you calculator have a small D at the top so you are working in degrees..?

Answer 15

nope

Answer 16

what does it have,,?

Answer 17

when I do (cos)^-1 97/182 I get 90

Answer 18

90 degrees

Answer 19

here is an online calculator

http://web2.0calc.com/

press these keys

2nd

acos

2nd

97 divide 182 )

then

=

Answer 20

and then I get 58.75 degrees

Answer 21

Its 57

Answer 22

57.79