① 楂樻暟奼傛瀬闄愭眰澶х炲憡璇夋垜鎴戝摢閲岄敊浜嗭紝鎴戠殑絳旀堟槸1錛屾ｇ『絳旀堟槸2錛
搴旇ヨ佸啀鐢ㄤ竴嬈℃礇蹇呰揪娉曞垯lim (1/cos^2x - 1/(1+x^2))/(1-cosx)鍒嗗瓙鍒嗘瘝閮借秼榪戜簬0錛岀敤媧涘繀杈炬硶鍒欙紝鍒嗗瓙鍒嗘瘝鍒嗗埆奼傚涓婂紡 = lim (2sinx/cos^3x + 2x/(1+x^2)^2)/ sinx= lin (2/cos^3x + 2x/sinx / (1+x^2)^2)= 4