如图11,抛物线和直线y=kx-4k(k(1)若点C的坐标为(-10,0)且tan∠DBO=3/4.求抛物线的解析式.(2)若对称轴是直线x=-1,且∠ABD=90°.求抛物线的解析式.
问题描述:
如图11,抛物线和直线y=kx-4k(k(1)若点C的坐标为(-10,0)且tan∠DBO=3/4.求抛物线的解析式.
(2)若对称轴是直线x=-1,且∠ABD=90°.求抛物线的解析式.
答
没见有图,所以按叙述做.如不一致,请发图.(1)直线 y = kx - 4k = k(x - 4)A(4,0),B(0,-4k)C(-10,0),对称轴x = (-10 + 4)/2 = -3y = a(x + 10)(x - 4)x = 0,y = -40a = -4k,k = 10atan∠DBO = 3/4 = DO/OB = 3/(-4k) k...