Answer:
:
Definition: 1 Mark
Proof: 1Mark
If two angles have the same measurement, they are congruent. Also, if two angles are congruent, their measurementsare same.
We know thatin everyright-angled triangle, one angle is ${90}^{\circ }$.
Example: Consider two right-angled triangles$\Delta AJU$ and $\Delta NIV$

In$\Delta AJU,\angle AJU={90}^{\circ }$
and in $\Delta NIV,\angle NIV={90}^{\circ }$
Since one angle is same in both, we can say that they have one pair of congruent angles.
So, if you take any two right-angled triangles, at least one pair of angles will be congruent, i.e. equal.