[填空题]
Oliver throws a coin fzo5ly f9ri4-3ch8fq n rom the8x 0iuuy( 709mt7mj j agutnt5 open window onto flat horizontal ground in front of his(u ux0 una79i 5gt jjmm8ty0t7 office building.
The path of the coin is modelled by the quadratic curve y=8+3x−0.5x2 , where $x$ represents the horizontal distance the coin is thrown and $y$ represents the height of the coin above the ground. All distances are measured in metres. The wall of the building lies along the $y$-axis. The coin starts its flight at point A, reaches its maximum height at point B, and lands on the ground at point C, as shown on the diagram below.
1.Write down the height in metres from which the coin was thrown. m
2.Calculate the maximum height, above the ground, reached by the coin. m
3.Find the horizontal distance from the base of the wall to the point at which the coin hits the ground. m