You are not logged in.
Pages: 1
I am having trouble with the topic
the question is find all the sine, cosine and tangent of alpha if sec alpha = -4sqrt5/5 and is in the second quadrant.
Offline
Let β = π − α, so β is acute and cos(β) = −cos(α).
Draw a right-angled triangle with hypotenuse
, one of the other sides 1 and the angle in between β. Then you haveThe length of the third side can be found by Pythagoras theorem; it is
So now you know all three sides of the right triangle, you should be able to work out the sine, cosine and tangent of β. Finally, since α is in the second quadrant, sine will be positive while cosine and tangent are negative, so adjust your signs accordingly for the sine, cosine and tangent of α.
Offline
Pages: 1