1. samalami

2. EulerGroupie

Use pythagorean theorem to get your third side, then use triangular trig ratios to get the trig functions... like sin(theta)=opp/hyp, cos(theta)=adj/hyp, etc...

3. EulerGroupie

There is a nice little short cut too... once you find sin, cos, and tan... csc, sec, and cot are the reciprocals.

4. samalami

@EulerGroupie is it A then??? the first choice?

5. EulerGroupie

That is not what I got. What did you get for the missing side?

6. samalami

12/3sqrt41

7. EulerGroupie

eek!$c ^{2}=a ^{2}+b ^{2}$where c is the hypotenuse. You have c and a... solve for b$b=\sqrt{c ^{2}-a ^{2}}$

8. EulerGroupie

It comes out nice... not irrational. What do you get for the missing side now?

9. samalami

9?

10. EulerGroupie

Yes

11. EulerGroupie

Now, all of those trig functions have angle A in them... so you are looking at the triangle from that corner. If that's the case, then 9 is your adjacent side, 12 is your opposite side, and 15 is the hypotenuse. So what is sin A=opp/hyp?

12. samalami

4/5

13. EulerGroupie

Yes! Now cos A=adj/hyp... which is?

14. samalami

3/4

15. samalami

sorry thats not it!!

16. EulerGroupie

Not what I got. adj=9, hyp=15...

17. samalami

3/5

18. EulerGroupie

Yes! tan?

19. samalami

what is the equation for tan?

20. EulerGroupie

21. samalami

4/3 :)

22. EulerGroupie

Yes!

23. samalami

thank you, I understand the rest now

24. EulerGroupie

Awesome! You're welcome.