The maximum height attained by projectile is increased by 10% by changing the angle of projection, without changing the speed of projection. The percentage increase in the time of flight will be

Given h=u2sin2⁡θ2g.Differentiating partially we get ∵v0= constant δh=u22g2 sin θ cos θ δθ. Thus δhh=2cos ⁡θδθsin ⁡θ=0.1(given).Therefore, cos ⁡θδθsin ⁡θ=0.05……(1)We also have T=2usin⁡ θg which gives δT=2ucos ⁡θδθg.Thus δTT=cos⁡ θδθsin ⁡θ. But using (1) we getδTT=0.05 or δT=0.05T.Hence, T increases by 5%.