Question

Mateeee..............​

Answer 1

Răspuns:

Explicație pas cu pas:

sina=√1-cos²a=√1-9/25=4/5

sinb=√1-9/16=√7/4

sin 2a=2sinacosa=2x4/5x3/5=24/25=0,96

cos2a=cos²a-sin²a=(3/5-4/5)(3/5+4/5)=-1/5x9/5=-9/25

sin (a-b)=sinaxcosa-sinbxcosb

             =4/5x3/5-√7/4x3/4=12/25-3√7/16

cos(a-b)=cosaxcosb+sinaxsinb=3/5x3/4+4/5x√7/4=9/20+4√7/20

Answer 2

Răspuns:

Explicație pas cu pas:

cos a = 3/5

cos b = 3/4

sin a = (1- (3/5)^2)^0.5=((25-9)/25)^0.5=4/5

sin b = (1- 9/16)^0.5=1/4 * r7

sin 2a = 2sin a * cos a = 2*3/5*4/5= 24/25

cos 2a = cos2 a-sin2 a= 9/25-16/25 = -7/25

sin(a-b) = sina *cosb - sinb* cosa =4/5*3/4-1/4*r7*3/5=3/20*(4 - r7)

cos (a+b) = cosa* cosb - sina *sinb= 3/5*3/4-4/5*1/4*r7=4/20*(1.25 - r7)