Question

determine the measure of angle b of the triangle.
the problem is attached in the post. help please

Answer 1

this is my work, where did i go wrong?

Answer 2

I have found that the error was in the use of sin theory

Answer 3

in a/sina=c/sinc math? if so im getting to rework, give me a moment. this math isnt even necessary in the problem. i shouldve said a/sina=b/sinb

Answer 4

yeah found it. angle c is larger than 90 degrees. so using sin inverse would not normally provide angles larger than 90. so you need to subtract 75 from 180 to get the real angle of c. do you understand it?

Answer 5

Using Law of Sines


a = 5.9616910353
A=46 degrees
b=4

a / sin(A) = b / sin (B)

sin(B) = b * sin(A) / a

sin(B) = 4 * 0.71934 / 5.96169

sin(B) = 2.87736 / 5.96169

sin (B) = 0.482641667

arc sine .482641667 = 28.858 Degrees

Answer 6

yes i got thaat part now but im going to rework a/sina=c/sinc

Answer 7

you should probably use a/sina = b/sinb or something like that. exclude sinc

Answer 8

yes for this particular problem your right. but if the problem asked for all sides and angles, it would be necessary so i want to add to problem to use for future notes.

Answer 9

value of sine against angle is a wave so the value of sin(angle) is repeated. thus use of arcsin would not return the correct angle as angle C is larger than 90 degrees

Answer 10

i dont understand that

Answer 11

so i should 180-b-a to find angle of c?

Answer 12

it means Sin(90) = Sin (270) , sin (0) =sin(180) . like that there are several angles that represent the same sine value

Answer 13

sorry sin(90) is not equal to sin 270.

Answer 14

iin other words. for this problem a/sina=c/sinc will not work to find angle c? i disagree hold on, ill upload proof let me finish working it out and i have to take pic with phone then email to laptop then upload here. give me 5 mins tops

Answer 15

@Harindu

Answer 16

all these angles add to 180

Answer 17

right; but how would you know that angle c is larger than 90 degrees without finding angle B first?

Answer 18

side 8 length is double side 4 length

Answer 19

is that a theory?

Answer 20

lol, no i seen it from the book

Answer 21

:)

Answer 22

i meant yes it is a true theory, i seen it done in my text book. it isnt my personal theory

Answer 23

yeah thats what i meant. bye

Answer 24

see it @Harindu

Answer 25

but it doesn't work with your example nw