How do we know that Tan(180-x)=-tanx And Cos(180-x)=-cosx Sin(180-x)=Sinx Tan(90-x)=1/-tanx etc...is there any way we can find out these?
1 Answer
Apr 20, 2018
See below
Explanation:
Let's try proving two them
Apply tangent sum identity:
Simplify:
The second one we will try is
Unfortunately
Apply quotient identity:
Now apply the sine and cosine sum identities:
Simplify:
Apply quotient identity:
Apply reciprocal identity: