triangle ABC b 10 ft c 7 ft angle B 70 degrees find angle A

triangle ABC b= 10 ft c= 7 ft angle B = 70 degrees find angle A please show work

Solution

by law of sines

b/sinB=c/sinC

10/sin70⁰= 7/sinC

sinC=(7/10)sin70⁰

sinC=0.6578

C=41.13^o

A+B+C =180^o

A+70⁰+41.13^o =180^o

A=68.87^o