Britwells

GIVE US SOME MORE INFO...THE ANGLE Y=100 DEGREES IS A CORESPONDING ANGLE OR THE ANGLE FORMED BY THE TWO SIDES a and b?

Anyway if the angle is the one formed by the two sides a and b yes there is triangle...

get the cosine rule to find the 3rd side and then apply again the cosine rule to find the other two angles...

as simple as such . good luck

MINOAS