描點(diǎn)法畫函數(shù)y=56x+cos(110x+39)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=56x+cos(110x+39)在區(qū)間[-EQ\F(4π+39,110),EQ\F(4π-39,110)]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?=56x和余弦函數(shù)y?=cos(110x+39)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=56x+cos(110x+39)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+39,110),EQ\F(4π-39,110)]為例，描點(diǎn)列為：x-0.469-0.462-0.455-0.447-0.440110x+39-4π-15π/4-7π/2-13π/4-3πcos(110x+39)10.710-0.71-156x-26.26-25.87-25.48-25.03-24.64y-25.26-25.16-25.48-25.74-25.64x-0.433-0.426-0.419-0.412-0.405110x+39-11π/4-5π/2-9π/4-2π-7π/4cos(110x+39)-0.7100.7110.7156x-24.25-23.86-23.46-23.07-22.68y-25.0-23.9-22.8-22.1-22.0x-0.397-0.390-0.383-0.376-0.369110x+39-3π/2-5π/4-π-3π/4-π/2cos(110x+39)0-0.71-1-0.71056x-22.23-21.84-21.45-21.06-20.66y-22.2-22.6-22.4-21.8-20.7x-0.362-0.355-0.347-0.340-0.333-0.326110x+39-π/40π/4π/23π/4πcos(110x+39)0.7110.7100.71-156x-20.27-19.88-19.43-19.04-18.65-18.26y-19.6-18.9-18.7-19.0-19.4-19.3x-0.319-0.312-0.305-0.297-0.290-0.283110x+395π/43π/27π/42π9π/45π/2cos(110x+39)-0.7100.7110.71056x-17.86-17.47-17.08-16.63-16.24-15.85y-18.6-17.5-16.4-15.6-15.5-15.8x-0.276-0.269-0.262-0.255-0.247-0.240110x+3911/4π3π13π/47π/215π/44πcos(110x+39)-0.71-1-0.7100.71156x-15.46-15.06-14.67-14.28-13.83-13.44y-16.2-16.1-15.4-14.3-13.1-12.4※.函數(shù)的示意圖y=56x+cos(110x+39) y (-0.240,-12.4)(-0.355,-18.9) x