please please check my answers

Question

18)Evaluate the sine cosine and tangent of the real number 

t=(4)(3.14)/3

 

My answer

Sin(t)=4/3

Cos(t)=3/4

Tan(t)=2/3

 

54)use a calculator to evaluate the expression.Round to the nearest hundredth 

Sec2.5

My answer

Sec 2.5=1/cos 2.5

=-1.67

Answer 1

Sin ( t) = Sin 4/3 ∏

 

  You should calculate it without using calculator, by using the Values of Special angles .

   

  Sin ( t) = Sin ( 4/3) ∏ = Sin ( ∏ + ∏/3 ) = - Sin ∏/3 = - √(3) /2

 

     Cos ( t ) = - Cos ∏/3 = - 1/2

 

      Tan ( t) = Sin ( t) / Cos t = - ( √3) /2  / - 1/ 2 = √3

 

      

Answer 2

4/3  x 3.14(pi) = 4.186 radians

 

convert radians to degress

 

2 pi(3.14) = 360 degrees

 

4/3   x  pi = 240 degree

 

sin 240 = sin(180+60) = -sin60 = - √3/2 =  -0.866

cos 240 = cos(180 + 60) = -cos60 = -1/2=  -0.5

tan 240 = sin240/cos240 =√3= 1.732 

 

54)

 

2.5 radian = 180/3.14   x 2.5 = 143.31 degrees

 

cos 143.312 = -0.80

sec 143.312 = -1.25

 

:)