设tan1234'+=a那么sin(-206')+cos(-206')的值为++
问题描述:
设tan1234'+=a那么sin(-206')+cos(-206')的值为
++
答
-(a+1)√1/(1+a^2).
答
sin(-206')+cos(-206')=sin26'-cos26'.因为:tan1234'=a=tan(180*8-206)'=tan(-206')=tan(-26-180)'=tan(-26)'.所以,sin26'=-acos26'.又sin^2(26')+cos^2(26')=1.所以,cos(26)'=√1/(1+a^2).所以,sin(-206')+cos(-20...