JAMB - Mathematics (1997 - No. 30)
The angle of elevation of a building from a measuring instrument placed on the ground is 30o. If the building is 40m high, how far is the instrument from the foot of the building?
\(\frac{20}{√3}\)m
\(\frac{40}{√3}\)m
20√3m
40√3m
คำอธิบาย
\(\frac{40}{x}\) = tan 30o
x = \(\frac{40}{tan 30}\)
= \(\frac{40}{1\sqrt{3}}\)
= 40√3m
x = \(\frac{40}{tan 30}\)
= \(\frac{40}{1\sqrt{3}}\)
= 40√3m