I changed 1,2 and 3 to a,b and c respectively to make notation easier. In a triangle side a is opposite angle A and so on.

Use the cos rule to find angle C:

Then you can use the sine rule rule to find A and/or B:

To find the last angle either use the sine rule again or (easier) take the other two angles from pi or 180 degrees

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edit: Since this is an isosceles triangle side a = side b and so angle A = angle B

Once you've found angle C you can do