Question

URGENT HELP: In ΔABC, if a = c = 16 centimeters and m∠B = 85°, what is b to two decimal places? I don't understand the Law of Sines when it comes to calculation...

Answer 1

@ikram002p

Answer 2

is it like this ?

Answer 3

if yes then m<A=m<C
k ?

Answer 4

I suppose, it doesn't come with a picture...

Answer 5

ohh then its like this :)
then
sin B/b =sin A /a=sin C/c

ok ?
just find m<A could u do that ?
remember m<A=m<C

Answer 6

Okay, give me one second...

Answer 7

Okay, um...I don't know, how would to rewrite it in the formula? I'm sorry, this is the first time I ever use this. I'm homeschooled. :\

Answer 8

Would it be something like sin85/16 for sinB/b or...? Because I was told to use the side opposite the angle.

Answer 9

well forget about sine law , angles sum of triangle is 180 right ? so let A snd C be x

so x+x+85=180 , solve for x

Answer 10

47.5 for both x's?

Answer 11

yes

Answer 12

NOW you can do the Law of sines

Answer 13

ok nw u can use law of sine ^_^
since u have m<A=m<B =x

Answer 14

Okay, but I don't understand out to do the Law of Sines...how would you plug in all the numbers?

Answer 15

you need a "pair" a side and its opposite angle
to form a ratio

you then set the ratios equal to each other

Answer 16

ok
so
sin B/b =sin A /a

then
sin 80 /b = sin 47.5 /16

solve for b

Answer 17

if you are looking for side b, then you need to use b!
so therefore you need to use its opposite angle B

that gives one ratio

now pick another side/angle pair

Answer 18

Okay, I am at a complete loss here...I wrote down here:

sin47.5/b = sin85/16 = sin47.5/16

So far so good?

Answer 19

you only use 2 out of the 3 ratios

and you can be flexible about how to write the ratios (if you know what you are doing).

But to stay "unconfused" for the time being
write sin(Angle) divided by its opposite side