Oxford PAT 2009, Questions 1 and 2

2009_page1

3 thoughts on “Oxford PAT 2009, Questions 1 and 2

  1. How do you know cos(t)=sqrt(1-sin^(t)) and not -sqrt(1-sin^(t))

    …with a minus sign? For example, when t=3pi/4, tan(t) should be negative. I think your formula should have a “plus-or-minus” sign in front of the fraction.

    1. Yes you are right, but the square root has an implicit plus or minus in front of it (i.e. the result of the square root can be positive or negative) and this also captures what you are saying.

      1. The notation √x represents the principal square root of x, which is positive.

        Every positive number a has two square roots: √a, which is positive, and −√a, which is negative. Together, these two roots are denoted ± √a

Add your comments

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s