The following table shows the degrees of the scale in which we find each type of triad:

Triad	Major Scale	Natural Minor Scale	Harmonic Minor Scale	Melodic Minor Scale
Major	I, IV, V	III, VI, VII	V, VI	IV, V
Minor	II, III, VI	I, IV, V	I, IV	I, II
Diminished	VII	II	II, VII	VI, VII
Augmented	-	-	III	III

Knowing the type of triad formed on each scale degree can be very helpful in identifying triads.