描點(diǎn)法畫(huà)函數(shù)y=53x+cos(162x+249)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(guò)描點(diǎn)法畫(huà)出三角函數(shù)y=53x+cos(162x+249)在區(qū)間[-EQ\F(4π+249,162),EQ\F(4π-249,162)]區(qū)間上圖像示意圖的主要過(guò)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?=53x和余弦函數(shù)y?=cos(162x+249)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=53x+cos(162x+249)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+249,162),EQ\F(4π-249,162)]為例，描點(diǎn)列為：x-1.615-1.610-1.605-1.600-1.595162x+249-4π-15π/4-7π/2-13π/4-3πcos(162x+249)10.710-0.71-153x-85.60-85.33-85.07-84.80-84.54y-84.60-84.62-85.07-85.51-85.54x-1.590-1.586-1.581-1.576-1.571162x+249-11π/4-5π/2-9π/4-2π-7π/4cos(162x+249)-0.7100.7110.7153x-84.27-84.06-83.79-83.53-83.26y-85.0-84.1-83.1-82.5-82.6x-1.566-1.561-1.556-1.552-1.547162x+249-3π/2-5π/4-π-3π/4-π/2cos(162x+249)0-0.71-1-0.71053x-83.00-82.73-82.47-82.26-81.99y-83.0-83.4-83.5-83.0-82.0x-1.542-1.537-1.532-1.527-1.522-1.518162x+249-π/40π/4π/23π/4πcos(162x+249)0.7110.7100.71-153x-81.73-81.46-81.20-80.93-80.67-80.45y-81.0-80.5-80.5-80.9-81.4-81.5x-1.513-1.508-1.503-1.498-1.493-1.489162x+2495π/43π/27π/42π9π/45π/2cos(162x+249)-0.7100.7110.71053x-80.19-79.92-79.66-79.39-79.13-78.92y-80.9-79.9-78.9-78.4-78.4-78.9x-1.484-1.479-1.474-1.469-1.464-1.459162x+24911/4π3π13π/47π/215π/44πcos(162x+249)-0.71-1-0.7100.71153x-78.65-78.39-78.12-77.86-77.59-77.33y-79.4-79.4-78.8-77.9-76.9-76.3※.函數(shù)的示意圖y=53x+cos(162x+249) y (-1.459,-76.3)(-1.537,-80.5) x