NTA Abhyas JEE Main2020MathematicsHeights and DistancesPractice
Let 10 vertical poles standing at equal distances on a straight line, subtend the same angle of elevation α at a point O on this line and all the poles are on the same side of O . If the height of the longest pole is h and the distance of the foot of the smallest pole from O is a ; then the distance between two consecutive poles, is
Options
- Ah sin α + a cos α 9 cos α
- Bh cos α - a s i n α 9 sin α
- Ch sin α + a cos α 9 sin α
- Dh cos α - a sin α 9 cos α
Correct answer
B. h cos α - a s i n α 9 sin α
Step-by-step solution
from diagram tan α = h a + 9 b a + 9 b = h cos α sin α 9 b = h cos α - a sin α sin α b = h cos α - a sin α 9 sin α