描點(diǎn)法畫函數(shù)y=228x+cos(98x+186)的性質(zhì)及其圖像主要內(nèi)容：本文根據(jù)余弦等函數(shù)的有關(guān)性質(zhì)，介紹通過描點(diǎn)法畫出三角函數(shù)y=228x+cos(98x+186)在區(qū)間[-EQ\F(4π+186,98),EQ\F(4π-186,98)]區(qū)間上圖像示意圖的主要過程與步驟?！?函數(shù)的定義域根據(jù)函數(shù)的特征，函數(shù)是一次函數(shù)y?=228x和余弦函數(shù)y?=cos(98x+186)的和函數(shù)，且二者的定義域?yàn)槿w實(shí)數(shù)，所以其和函數(shù)的定義域也為全體實(shí)數(shù)，即為:(-∞，+∞)?！?函數(shù)描點(diǎn)思路由于函數(shù)y=228x+cos(98x+186)含有三角余弦函數(shù)，三角函數(shù)具有周期性值，故描點(diǎn)以三角函數(shù)為中心函數(shù)，分別取三角函數(shù)值為0，±1以及45°角時(shí)的取值為本例函數(shù)的特征點(diǎn)?！?函數(shù)的部分點(diǎn)圖本處以區(qū)間[-EQ\F(4π+186,98),EQ\F(4π-186,98)]為例，描點(diǎn)列為：x-2.026-2.018-2.010-2.002-1.99498x+186-4π-15π/4-7π/2-13π/4-3πcos(98x+186)10.710-0.71-1228x-461.93-460.10-458.28-456.46-454.63y-460.93-459.39-458.28-457.17-455.63x-1.986-1.978-1.970-1.962-1.95498x+186-11π/4-5π/2-9π/4-2π-7π/4cos(98x+186)-0.7100.7110.71228x-452.81-450.98-449.16-447.34-445.51y-453.5-451.0-448.5-446.3-444.8x-1.946-1.938-1.930-1.922-1.91498x+186-3π/2-5π/4-π-3π/4-π/2cos(98x+186)0-0.71-1-0.710228x-443.69-441.86-440.04-438.22-436.39y-443.7-442.6-441.0-438.9-436.4x-1.906-1.898-1.890-1.882-1.874-1.86698x+186-π/40π/4π/23π/4πcos(98x+186)0.7110.7100.71-1228x-434.57-432.74-430.92-429.10-427.27-425.45y-433.9-431.7-430.2-429.1-428.0-426.4x-1.858-1.850-1.842-1.834-1.826-1.81898x+1865π/43π/27π/42π9π/45π/2cos(98x+186)-0.7100.7110.710228x-423.62-421.80-419.98-418.15-416.33-414.50y-424.3-421.8-419.3-417.2-415.6-414.5x-1.810-1.802-1.794-1.786-1.778-1.77098x+18611/4π3π13π/47π/215π/44πcos(98x+186)-0.71-1-0.7100.711228x-412.68-410.86-409.03-407.21-405.38-403.56y-413.4-411.9-409.7-407.2-404.7-402.6※.函數(shù)的示意圖y=228x+cos(98x+186) y (-1.770,-402.6)(-1.898,-431.7) x