Simplify Trigonometric Expressions...2

[nycmathguy]

Section 5.1

Question 20

cos(pi/2 - x)sex x

I know that pi/2 = 90 degrees.

Cos (90° – x) = Sin x.

We now have sin x• sec x.

I also know that sec x = 1/ sin x.

From this we get sin x • 1/sin x.

sin x • (1/sin x) = sin x/sin x = 1.

Answer: 1

You say?

 

[MathLover1]

sec x = 1/ cos x

then you have sin x/cos x = tan(x)

 

[nycmathguy]

sec x = 1/ cos x

then you have sin x/cos x = tan(x)

I see my error.

sec x = 1/cos x.

Then sin x• 1/cos x = sin x/cos x = tan x.