For angles theta and (90 - theta):

• R(theta) = u^2sin(2theta)/g
• R(90-theta) = u^2sin(2(90-theta))/g = u^2sin(180-2theta)/g = u^2sin(2theta)/g

Therefore R(theta) = R(90-theta).

But heights differ:

• H(theta) = u^2*sin^2(theta)/(2g)
• H(90-theta) = u^2*cos^2(theta)/(2g)
• Ratio: H(theta)/H(90-theta) = tan^2(theta)

And flight times differ:

• T(theta) = 2u*sin(theta)/g
• T(90-theta) = 2u*cos(theta)/g
• Ratio: T(theta)/T(90-theta) = tan(theta)

JEE favorite: RH relationship: R = 4H*cot(theta)