287^2-287*48+239*713 = 287*(287-48) + 239*713 = 287 * 239 + 239*713 =
239*(287+713)=239*1000 = 239000
==============================================
73.4^2+73.4*17.2-90.6*63.4 = 73.4*(73.4 + 17.2) = 73.4 * 90.6 - 90.6 * 63.4 =
90.6*(73.4-63.4)=90.6*10=906
Ответом будет .................................1)
arctg (-1)-arctg 1=3pi/4-pi/4=2pi/4=pi/2
arcsin( -1)-arccos (-<span>√2/2)=3pi/2-3pi/4=6pi/4-3pi/4=3pi/4</span>
<span>arcsin (-1/2)-arctg 1/<span>√3=7pi/6-pi/6=6pi/6=pi</span></span>
<span><span>arcsin 1+arcctg <span>√3=pi/2+pi/3=3pi/6+2pi/6=5pi/6</span></span></span>