UPSC CDS Math Height and Distances Questions

Here, AB is the building and CD isthe tree.Here, AB is the building and CD is the tree.
Let the height of the tree be h m.
AB = 90 m and CD = h m.
∴ BE = AB – AE = AB – CD
= (90 – h) m
In right ΔABC
tan‌45°=1=

AB

AC

⇒ AC = 90m
In right ΔBDE
tan‌30°=

1

√3

=

BE

DE

⇒

1

√3

=

90−h

90

 (DE=AC)
⇒90−h=30√3
⇒h=(90−30√3)m