Angle A is 91°
In order to get to that answer, you have to remember your SOHCAHTOA method (Or Sin= Opp/Hyp Cos= Adj/Hyp and Tan= Opp/Adj)
So first try to find Angle C, you would use SOH. So Sin C = 7/14 (7 is your opposite and 14 is your hypotenuse) Which when you inverse Sin (or Sin^-1) the 7/14, in degrees, you should end up with 30°. Next do the same thing to Angle B but this time instead of 7/14, it's now gonna be Sin B= 12/14 (12 being opposite to B and 14 being the hypotenuse) and then you Inverse Sine (Or Sin^-1) the 12/14 and you should get 59°.
At this point, you should know basic angle solving skills. Which being Angle C + Angle B + Angle A = 180. Plug in the two you know, so 30+59+Angle A= 180
89+ Angle A = 180
180-89= 91°
Final solution: Angle A = 91°
