Evaluate:tan260cot640
To evaluate : tan260cot640
We can write 260 as 260=(900-640)
So tan260=tan(900-640)
⇒ tan260=cot640 [Formula used: tan(900-θ)=cotθ]
Now, replacing the value of tan260from the above, we get
tan260cot640=cot720cot720
Thus,tan260cot640=1