Alright, lets get started.
We could use sine law to find the remaining angle.
[tex] \frac{sinA}{a} = \frac{sinB}{b} [/tex]
[tex] \frac{sinS}{63.6} = \frac{sin64}{69.8} [/tex]
Plugging the value of sin 64
[tex] \frac{sinS}{63.6} = \frac{0.8987}{69.8} [/tex]
[tex] \frac{sinS}{63.6} = 0.01287 [/tex]
Cross multiplying
sin S = 0.8189
Taking inverse on both side
[tex] S = sin^{-1}(0.8189) [/tex]
S = 55° : Answer
Hope it will help :)
