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.

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