Michigan State University - Diagnostic Exam

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6.15

  •   Which of the following is equal to the expression, --cos-x-- 1 + sinx ?

    a) cos x + cot x b) cos x + tan x c) sec x
         
    d) sec x + tan x e) sec x - tan x

Solution:

--cosx--- --cosx---1---sinx- 1 + sin x = 1 + sin x 1 - sinx = cosx-(1---sin-x)- 1 - sin2 x cosx-(1---sin-x)- = cos2x = (1---sin-x)- cosx --1-- sinx- = cosx - cosx = secx - tan x

Diagnostic:

See 6.4: Trigonometric Identities .

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July 15, 2008