Question

____________Вычислите____________

Answer 1

$cos(90+10) sqrt{sin^2(90-21)+cos^221*tg^2(180-10)} /cos(180+21)=$$-cos10 sqrt{cos^221+cos^221*tg^210}/(-cos21)=$$cos10*cos21 sqrt{1+tg^210} /cos21=cos10 sqrt{1/cos^210}=cos10*1/cos10=$$1$

Answer 2

cos(90+10) НЕ РАВЕН -cos(10)