Maths Problem

jumpguy

Was revising maths tonight and I came across a problem. I couldn't for the life of me remember what to do. So I turn to you all-knowing boardsies for help!

For those of you with Text and Tests 4, it's Exercise 2C Question 11 and 12

Q11. If Cos A = -11/13 and sin A is positive, express Tan A as a fraction.

I know it's related to the unit circle, but I can't covert the Cos into degrees

Q12. If Cos A = 0.7986 and Tan A is negative, find the value of sin A. (0 Degrees is Less Than A which is Less Than 360 Degrees).



Please explain how to do 'em, the answer is of no help (just revising, not h/w). Thanks in advance!

Johnny Giles

H/L Maths.

God No.

clartharlear

Because cos is negative and sin is positive, from the unit circle, you know that tan is negative.

Draw a right-angled triangle for which Cos A = 11/13 [C = A/H] and use Pythagoras to find the third side (opposite).

Tan A = O/A.

Leave the answer in surd form since they ask you for a fraction.

Tan A = -(sqrt48)/11

blubloblu

Tan = sin/cos
how could it possibly be positive?
And cos is A/H. Which makes that a 11,12,13 triangle, much easier.