Trigonometric Function

• Minnesota Jen

  24 Jul 09, 23:02

  Please help to solve the following question :

   

  It is given that cos 70� = h and sin 35� = k. Without using tables or a calculator,

  show that h + 2k^2 = 1.

   

   

• Mikethm

  24 Jul 09, 23:46

  Originally posted by Minnesota Jen:

  Please help to solve the following question :

   

  It is given that cos 70� = h and sin 35� = k. Without using tables or a calculator,

  show that h + 2k^2 = 1.

   

  
   sin^2 (35) + cos^2 (35) =1

  Using cos (70) = 2cos^2 (35) -1 aka cos^2 (35) = 0.5cos (70) + 0.5

  k^2 + [ 0.5cos (70) + 0.5] =1

  k^2 + 0.5h = 0.5

  2k^2 + h = 1 (shown)

• Minnesota Jen

  25 Jul 09, 18:33

  Thank you your answer It is of great help to me. Have a nice day~