Sin, and Cosin

Having some problems with 2 problems in calculus.

Find the value of Sin(a) if a is in the third quadrant and Cos(a) = -24/25

Find the value of Cos(a) if Sin(a)= 40/41 and Cos(a)<0

>>1
sin(a) = -7/25

>>2
sin(a) = -9/41

>>3
correction

cos(a) = -9/41

This isn't calculus, it's math analysis (I'm in it right now)

Simply graph the triangle-circle in the third quadrant, and label the appropriate sides -24 and 25. Solve for the missing side. Then proceed to use the missing side to find the value of Sin(a)

Here is the source of your difficulty.  While Sin is defined as the conscious, willful, premeditated act of an action which is known by the perpetrator to be against the will of God, at the time of the act, Cosin is a far more loosely defined "lesser evil", akin to the relationship between murder and manslaughter, wherein one or more of the adjectives given above may be omitted (The person committed the killing unwillingly or unwittingly, the wife did not intend to cuckold her husband and was instead taken, the person was ignorant of the Kingdom of the Lord, etc).

Use this fact, together with the Phillippian identity, and you will be able to readily solve all worthwhile mathematical questions over the course of your mathematical life.

oh

>>1 , I'm >>6 , and here's an actual helpful answer.  Simply recognize that {7,24,25} is a pythagorean triple (figure it out if you don't know) and work from there.  But this has been stated already and I need another beer.