Question

Exercitiul 8 va rog!

Answer 1

Răspuns:

Explicație pas cu pas:

Avem  R=((r2-1)^2+1^2)^0.5 =A

sin2a = (r2-1)/A

cos 2a = 1/A

sin 4a= 2*(r2-1)/A^2

cos 4a = 1/A2- (r2-1)^2/A2=2*(r2-1)/A2

tg 4a = sin 4a/cos 4a= 1

b)   R=(2^2+3^2)^0.5=r13

sin x/2= -2/r13

cos x/2= 3/r13

sin x=-12/13

cos x= 5/13

(2+3cos x)/(4-5sinx)= (2+3*5/13)/(4+5*12/13)= 41/112

c)  R= (p2+q2)^0.5=A

sin a = p/A

cos a = q/A

sin 2a = 2pq/A2

cos 2a= (q2-p2)/A2

p*2pq/A2+q*(q2-p2)/A2=(2p2q+q3-p2q)/A2=(p2q+q3)(p2+q2)