Question

计算下列计算题,要写过程1.6sin(-90°）+3sin0°-8sin270°+12cos180°2.10cos270

Answer 1

(1)3001^2 =（3000 1）^2 =3000^2 2×3000×1 1^2 =9000000 6000 1 =9006001 （2）901*899 =（900 1）（900-1） =900^2-1^2 =810000-1 =809999 (3)999^2-1 =(999-1)(999 1) =998*1000 =998000 (4)321^2-322*320 =321...