Given the triangle below, find angle A

Question

Given the triangle below, find angle A.

 

 

         B

       /   \

      / 73°\

     /        \ 6.4

    /           \

A /_________\ C

        7.1

Answer 1

you can use the law of sines

a/sinA=b/sinB=c/sinC

a/sinA=b/sinB  where a=6.4 , b=7.1 and angle B=73º

6.4/sinA=7.1/sin73º

6.4/sinA=7.1/(0.956304755)

7.1(sinA)=6.4(0.956304755)

7.1(sinA)=6.120350432

sinA=6.120350432/7.1

sinA=0.862021187

using arcsin on your calculator...

A=59.54428476º

A=59º 32' 39.425"

Answer 2

For this problem, you may use the Law of Sines which states:

 

a/Sin A = b/SinB

 

6.4/Sin A = 7.1/Sin (73)

 

7.1 (Sin A) = 6.4 (Sin 73)

 

Sin A = [6.4(Sin 73)]/7.1

 

inverse Sin [6.4(Sin 73)/7.1 = A

 

A = 59.5 degrees

 

Hope this helps!