Answer:
In [tex]\triangle shd[/tex] and [tex]\triangle std[/tex]
[tex]sd \perp ht[/tex]
By definition of perpendicular: Lines that are right angle to each other.
[tex]\angle sdh \cong \angle sdt = 90^{\circ}[/tex] [Right angle]
[tex]sh \cong st[/tex] [Hypotenuse side] [Given]
Transitive property says that segment is congruent to itself.
[tex]sd \cong sd[/tex] [By transitive property]
HL theorem states that if the hypotenuse and one leg of right triangle are equal to the hypotenuse and one leg of the another right angle , then the two triangle are congruent.
then by HL theorem;
[tex]\triangle shd \cong \triangle std[/tex] proved!