求下列各式的值 (2)a²sin810°+b²tan765°+(a²-b²)tan1125°-2abcos360°
问题描述:
求下列各式的值 (2)a²sin810°+b²tan765°+(a²-b²)tan1125°-2abcos360°
答
a²sin810°+b²tan765°+(a²-b²)tan1125°-2abcos360°=a²sin(2×360°+90°)+b²tan(2×360°+45°)+(a²-b²)tan(3×360°+45°)-2abcos360°=a²sin(90°)+b²tan(4...