[填空题]
Kai launches stones from a slu* x+4,(g pa/muvm c zdptmu59ingshot int:8eh 5bgn/pe9uqki )lo the air. Each time he launches a stone, he records the ele: 5n98 /)qubgkhpi angle, \theta , in degrees, at which the stone is launched, and the horizontal distance, L , in metres, which the stone travels from his shooting position to where it first lands. The diagram below illustrates how the stones travel in the air when launched at different angles.
1. Determine whether the graph of L versus \theta is at $\theta= 50^{\circ}$ .
Kai observes that when the angle is $30^{\circ} $, the sling stone will travel a horizontal distance of $90 \mathrm{~m}$ .
2. Find an expression for L in terms of $\theta$ .
L= -0.04$\theta$$^2$+ a$\theta$+b ;a= ,b= .