Respostas

  • Usuário do Brainly
2014-08-31T02:19:13-03:00
Vamos aplicar lei dos cossenos

 d^{2} = 10^{2} + 14^{2} -2.10.14.cos 60

 d^{2} =100+196-280. \frac{1}{2}

 d^{2} =296-140

 d^{2} =156

d= \sqrt{156} = \sqrt{ 2^{2}.3.13 }

d=2 \sqrt{39} cm


 D^{2} = 10^{2} + 14^{2} -2.10.14.cos120

 D^{2} =100+196-2.10.14.(-cos60)

 D^{2} =296-280.(- \frac{1}{2} )

 D^{2} =296+140

 D^{2} =436

D= \sqrt{486} = \sqrt{ 2^{2}.109 }

D=2 \sqrt{109} cm