Right circular cone has a height 40cm and its semi vertical angle is 45° then radius of its base circle is
(a) 40cm
(b) 80cm
(c) [(40√3)/2]cm
(d) 20cm
The correct option (a) 40cm
Explanation:
given: α = 45°, h= 40cm
from diagram,
tanα = (r/h)
∴ tan45 = (r/40)
∴ r = 40cm
i.e. base radius = 40cm.
