已知直线l的倾斜角为α,且45°≤α≤135°,求直线l的斜率k的取值范围是 直线l的斜率为k的倾斜角为a，若45°﹤a﹤135°，则k的...
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k > 1 or k < - 1.
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[45,90)和（90,135]
tg45=1,tg135=-1
所以取值是（-无穷大，-1）和(1，正无穷大）
k=tana tana在 45°<=α<90°上单调增加，k>=1,90°<a<=135°单调增加k<=-1
k>=1或k<=-1 a=90°k趋向于无穷大即直线x=a
绛旓細鐩寸嚎L1鐨勫炬枩瑙掍负45搴 鑻ョ洿绾縇2鍨傜洿浜嶭1,鎵浠ョ洿绾縇2鍊炬枩瑙掍负45+90=135掳 鐩寸嚎L2鏂滅巼k=tan135掳=-1 鑻ョ洿绾縇2鍦╕杞翠笂鐨勬埅鐭╀负-1 鎵浠ョ洿绾縇2鏂圭▼锛歽=kx+b=-x-1
绛旓細璁剧洿绾跨殑鏂圭▼涓烘啫姘﹀皝鏁欒帺瀵勫嚖鐘鑴瘬y=kx+b 鈭鐩寸嚎l鐨勫炬枩瑙掍负45搴,鈭磌=1 涓旂粡杩囩偣(-1,0),浠ｅ叆0=-1+b b=1 鍒欑洿绾縧鐨勬柟绋嬩负y=x+1
绛旓細绗竴闂
绛旓細鐩寸嚎l鐨勫炬枩瑙掍负伪锛鑻 cos伪=45锛屽垯伪鐨勭粓杈瑰湪绗-璞￠檺锛屾晠sin伪=35锛屾晠l鐨勬枩鐜囦负tan伪=sin伪cos伪=34锛屽張鍥犱负鐩寸嚎l鍦▂杞翠笂鐨勬埅璺濅负-5鈭寸洿绾縧鐨勬柟绋嬫槸锛歽=34x-5鍗筹細3x-4y-20=0锛庢晠绛旀涓猴細3x-4y-20=0锛
绛旓細鐩寸嚎L鐨勫炬枩瑙掍负45搴 閭ｄ箞鐩寸嚎鏂滅巼k=1 鐩寸嚎L杩囩偣M(1,2)鍙啓鍑虹洿绾挎柟绋嬶細y-2=x-1锛屽嵆 y=x+1 鍦咰杩囩偣A(1,1)锛孊(2,-2)鎵浠ュ渾蹇僀鍦ˋB鐨勪腑鍨傜嚎涓 鍙眰寰桝B鏂滅巼涓-3锛屼腑鐐瑰潗鏍囦负(3/2, -1/2)鎵浠ヤ腑鍨傜嚎鏂圭▼锛歽 +1/2 = (1/3)*(x -3/2)锛屽嵆 3y=x-3 鑱旂珛涓ゆ潯鐩寸嚎鏂圭▼锛...
绛旓細瑙ｏ細璁鐩寸嚎l鐨鏂滅巼涓簁锛屽垯k=tan45掳=1锛屾墍浠ョ洿绾縧鐨勬柟绋嬩负锛歽-1=1脳锛坸-0锛夊嵆x-y+1=0 鏁呴堿
绛旓細鍥犱负鐩寸嚎鍊炬枩瑙掍负45掳锛屾墍浠ユ枩鐜囦负1鍥犱负杩囩偣(-2,3)鎵浠ョ洿绾挎柟绋媦-3=x+2x-y+5=0
绛旓細鐩寸嚎L鐨勫炬枩瑙掍负45掳锛岄偅涔堟枩鐜噆=1 璁綥:y=x+m浠ｅ叆x²/2+y²=1 寰楋細x²/2+(x+m)²=1 鏁寸悊锛3x²+4mx+2m²-2=0 璁続(x1,y1),B(x2,y2),鏍规嵁闊﹁揪瀹氱悊锛歺1+x2=-4m/3,x1x2=(2m²-2)/3 鏍规嵁寮﹂暱鍏紡锛殀AB|=鈭(1+1)*鈭歔(x1+x2...
绛旓細鐩寸嚎L鐨勫炬枩瑙掍负45搴 鐩寸嚎鏂滅巼涓 tan45掳=1 鐩寸嚎L鍒板師鐐圭殑鍧愭爣涓 x²+y²=5²2x²=25 x=卤5鈭2/2 y=∓5鈭2/2 鐩寸嚎鏂圭▼涓 y=x+b b=2脳锛埪5鈭2/2锛=卤5鈭2 鐩寸嚎鏂圭▼涓 y=x+5鈭2鎴杫=x-5鈭2 ...
绛旓細鍊炬枩瑙45搴,鍒 k=1 銆恔=tan45搴=1銆l鐨鏂圭▼涓 y-5=x-2 => x-y+3=0 涓烘墍姹傘
