In triangle △TUV, since it is isosceles with ∠T ≅ ∠V, we know that the measures of angles T and V are equal.
Given that m∠U = 54°, we can use the fact that the sum of the interior angles of a triangle is 180°:
\[ m∠T + m∠T + m∠U = 180° \] \[ 2m∠T + 54° = 180° \] \[ 2m∠T = 180° - 54° \] \[ 2m∠T = 126° \] \[ m∠T = \frac{126°}{2} \] \[ m∠T = 63° \]
So, the measure of angle T is 63°.
The correct answer is: m∠T = 63°.