UPSC CDS Math Height and Distances Questions

Suppose the height of the lower plane above the ground be h m.Let B and C be the positions of the lower plane and higher plane above the ground respectively. Also, consider D to be the position of the point on the ground AD.
Here, AB = h m and AC = 300 m.
In right ΔABD:
tan‌45°=1=

AB

AD

⇒ AD = h m
In right ΔACD:
tan‌60°=√3=

AC

AD

⇒√3=

300

h

⇒h=

300

√3

=100√3m