Posted by **Bobby** on Tuesday, June 29, 2010 at 3:59pm.

What is the angle B?

Given that

A=46 degree

b=4

c=8

- trig -
**bobpursley**, Tuesday, June 29, 2010 at 4:38pm
Is this a triangle?

Law of Cosines:

a^2=b^2+c^2-2bcCosA

solve for a.

Then, law of sines:

sin46/a=sinB/b

solve for sinB, then B

- trig -
**Henry**, Tuesday, June 29, 2010 at 5:20pm
LAW OF COSINES: CosA=(b^2+c^2-a^2)/2bc

Cos46=(16+64-a^2)/2*4*8.

Cos46=(80-a^2)/64, 80-a^2=64Cos46,

a^2=80-64Cos46=35.54, a=5.96=6.0

LAW of SINES: SinB/b=SinA/a

SinB/4=Sin46/6,Multiply both sides by 4: SinB=4*Sin46/6=0.4791, B=28.66=28.7

- trig -
**bobpursley**, Tuesday, June 29, 2010 at 5:28pm
and easy way to check this is to grab your protractor and sketch it to see if it works.

## Answer This Question

## Related Questions

- Johan - Given angle 1 = (x + 7)degree, angle 2 = *(2x -3)degree, angle ABC = (x ...
- math - Find an angle between 0 degree and 360 degree that is coterminal with ...
- Trig - I need help setting these up. 1.) Use the parallelogram rule to find the ...
- trig - given the following values, what is angle B? A= 46 degree b= 4 c= 8
- Trig - I need help with my vectors unit. I'm really confused about how to set ...
- math - In triangle ABC, angle B = 3, angle A and angle C = 8 angle A. How many ...
- Math Trig - I'll do my best to describe this problem. Given A=17 degrees, B=73 ...
- Trig-Value of angle degree - For the angle degree 0, i don't understand how for ...
- trig - Given angle x,where 0 <= x <= 360 (degrees) solve for to the ...
- trig - When the sun's angle of elevation is 30 degree the shadow of a post is 6 ...

More Related Questions