[67_Camaro_Chic]

if anyone can by any chance explain to me some tricks to using sine, cosine, tangent, cosecant, secant, and cotangent.. PLEASE let me know... i need help...

and if anyone wants to know a trick... squaring any number that ends in 5... here's a trick...

(105)^2.. take 10, and the next number up is 11.. multiply the 2 together...

10x11=110 5 squared is 25.. add 25 to the end

105^2=11025

75^2= 7x8=54(add25)=5425

15^2= 1x2=2(add25)=225

get it? it's easy!!!!!

[Mike Graham]

Tricks? There are not any good numerical tricks really (other than perhaps that sin(w) is approximately w with very small numbers.)

Knowing how they relate to each other is important

tan(x)=sin(x)/cos(x)
sec(x)=1/cos(x)
csc(x)=1/sin(x)
cot(x)=cos(x)/sin(x)

and so forth.

And also to understand that sin and cosine are no so different from each other. sin(x)=cos(90-x). So they are all a matter of sine of something.

Also, identities like the square, double-angle and half-angle identities will be haunting you as for a long time if youc ontinue pursuing math.

sin²(q)+cos²(q)=1 (ie sin²(q)=1-cos²(q), etc.)
sin(2q)=2*sin(q)cos(q)
cos(2q)=2cos²(q)-1 (think about applying the first identity to this)
from this you could easily derive tan²(q)
sin²(q/2)=(1/2)*(1-cos(q))
cos²(q/2)=(1/2)*(1+cos(q))