30.已知:如图14.抛物线与轴交于点.点.与直线相交于点.点.直线与轴交于点. (1)写出直线的解析式. (2)求的面积. (3)若点在线段上以每秒1个单位长度的速度从向运动(不与重合).同时.点在射线上以每秒2个单位长度的速度从向运动.设运动时间为秒.请写出的面积与的函数关系式.并求出点运动多少时间时.的面积最大.最大面积是多少? 解:(1)在中.令 . .··············································· 1分 又点在上 的解析式为·············································································· 2分 (2)由.得 ···················································· 4分 . .······························································································· 5分 ························································································· 6分 (3)过点作于点 ······························································································· 7分 ·········································································································· 8分 由直线可得: 在中...则 .······················································································· 9分 ···················································································· 10分 ····························································································· 11分 此抛物线开口向下.当时. 当点运动2秒时.的面积达到最大.最大为.···························· 12分 查看更多

 

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已知:如图14,⊙A与轴交于C、D两点,圆心A的坐标为(1,0),⊙A的半径为,过点C作⊙A的切线交轴于点B(-4,0)
(1)求切线BC的解析式;
(2)若点P是第一象限内⊙A上的一点,过点P作⊙A的切线与直线BC相交于点G,且∠CGP=120°,求点G的坐标.

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已知:如图14,⊙A与轴交于C、D两点,圆心A的坐标为(1,0),⊙A的半径为,过点C作⊙A的切线交轴于点B(-4,0).
(1)求切线BC的解析式;
(2)若点P是第一象限内⊙A上的一点,过点P作⊙A的切线与直线BC相交于点G,且∠CGP=120°,求点G的坐标.

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已知:如图14,⊙A与轴交于C、D两点,圆心A的坐标为(1,0),⊙A的半径为,过点C作⊙A的切线交轴于点B(-4,0)
(1)求切线BC的解析式;
(2)若点P是第一象限内⊙A上的一点,过点P作⊙A的切线与直线BC相交于点G,且∠CGP=120°,求点G的坐标.

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已知:如图14,抛物线轴交于点,点,与直线相交于点,点,直线轴交于点

(1)写出直线的解析式.

(2)求的面积.

(3)若点在线段上以每秒1个单位长度的速度从运动(不与重合),同时,点在射线上以每秒2个单位长度的速度从运动.设运动时间为秒,请写出的面积的函数关系式,并求出点运动多少时间时,的面积最大,最大面积是多少?

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已知:如图14,在△ABC中,D为AB边上一点,∠A=36°,AC=BC,AC2=AB·AD.

(1)试说明:△ADC和△BDC都是等腰三角形;

(2)若AB=1,求AC的值;

(3)请你构造一个等腰梯形,使得该梯形连同它的两条对角线得到8个等腰三角形.(标明各角的度数)

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