Given: Distance from the point of observation =10km The aeroplane is at a height of 8km above the ground Concept used: sinθ=P∕H Here P= Perpendicular, H= Hypotenuse
According to the question, AC=10km So, sinθ=AB∕AC ⇒sinθ=8∕10=4∕5=0.8 Since, sin45∘=1∕√2≈0.71 sin60∘=√3∕2≈0.87 As, 0.71≤sinθ≤0.87 ⇒45∘≤θ≤60∘ ∴ Required answer is 45∘<θ<60∘