Question

1) Obtenha o valor de:

a) Sen135o=

b) Cos135o=

c) Sen150o=

d) Cos150o=


2) Determine o valor de x nas seguintes expressões:

a) x = sen 40o – sen 140o + cos 20o + cos 160o

b) x= sen20o- sem 160o+ cos44o+ cos136°

c)x=sen10o.cos50+cos130o.sen170o



ME AJUDE PFV

Answer 1

1)

a)

$\mathtt{sen(135^{\circ})=sen(45^{\circ})=\dfrac{\sqrt{2}}{2}}$

b)

$\mathtt{cos(135^{\circ})=cos(45^{\circ})=\dfrac{\sqrt{2}}{2}}$

c)

$\mathtt{sen(150^{\circ})=sen(30^{\circ})=\dfrac{1}{2}}$

d)

$\mathtt{cos(150^{\circ})=-cos(30^{\circ})=-\dfrac{\sqrt{3}}{2}}$

2)

a)

$\mathtt{x=sen(40^{\circ})-sen(140^{\circ})+cos(20^{\circ})+cos(160^{\circ})}\\\mathtt{x=sen(40^{\circ})-sen(40^{\circ})+cos(20^{\circ})-cos(20^{\circ})=0}$

b)

$\mathtt{x=sen(20^{\circ})-sen(160^{\circ})+cos(20^{\circ})+cos(160^{\circ})}\\\mathtt{x=sen(20^{\circ})-sen(20^{\circ})+cos(20^{\circ})-cos(20^{\circ})=0}$

c)

$\mathtt{x=sen(10^{\circ}).cos(50^{\circ})+cos(130^{\circ}).sen(170^{\circ})}\\\mathtt{x=sen(10^{\circ}).cos(50^{\circ})-cos(50^{\circ}).sen(10^{\circ})=0}$