Question

Решите плизззззззззз !!!! оч надо_О...

Answer 1

1)(sin^2a+cos^2a)^2=1

2)sin^2a+cos^2a+2sinacosa+sin^2a+cos^2a-2sinacosa=2(sin^2a+cos^2a)=2

3)(sin^2a+cos^2a)(sin^a-cos^2a)+cos^2a=sin^2a

4) cos^2a+sin^2a(sin^2a+co^2a)=cos^2a+sin^2a=1

5)1/sina-cosa/sina*cosa=(1-cos^2a)/sina=sina

Answer 2

1)$sin^4 a+2sin^2 acos^2 a+cos^4 a=(sin^2 a)^2+2sin^2 acos^2 a+(cos^2 a)^2=(sin^2 a+cos^2 a)^2=1^2=1$

 

2) (sin a+cos a)^2+(sin a-cos a)^2=sin^2 a+2sina cos a+cos^2 a+sin^2 a-2sina cos a+cos^2 a=2sin^2 a+2cos^2 a=2(sin^2 a+cos^2 a)=2*1=2[/tex]

 

3) $sin^4 a-cos^4 a+cos^2 a=(sin^2 a)^2-(cos^2 a)^2+cos^2 a=(sin^2 a-cos^2 a)(sin^2 a+cos^2 a)+cos^2 a=(sin^2 a-cos^2 a)*1+cos^2 a=sin^2 a-cos^2 a+cos^2 a=sin^2 a$

 

4) $cos^2 a+sin^4 a+sin^2 acos^2 a=cos^2 a+sin^2 a(sin^2 a+cos^2 a)=cos^2 a+sin^2 a*1=cos^2 a+sin^2 a=1$

 

5) $frac{cos a*tg a}{sin^2 a}-ctg a cos a=frac{sin a}{sin^2 a}-frac{cos^2 a}{sin a}=frac{1}{sin a}-frac{cos^2 a}{sin a}=frac{1-cos^2 a}{sin a}=frac{sin^2 a}{sin a}=sin a$