Question

CONTENT QUALITY REQUIRED
tan 10°. tan 20°. tan 30°. ....... tan 80° is:
a). 0 b). 1
c). -1 d). 24

#APEX GUIDE FOR ALIGARH MUSLIM UNIVERSITY ENTRANCE TEST

Answer 1

=(tan10∘tan80∘)(tan20∘tan70∘)(tan30∘tan60∘)(tan40∘tan50∘)=(tan⁡10∘tan⁡80∘)(tan⁡20∘tan⁡70∘)(tan⁡30∘tan⁡60∘)(tan⁡40∘tan⁡50∘)

=(1)(1)(1)(1)=1

so B) right answer

Answer 2

b) 1
TanA=Cot(90-A)
Thus tan10=cot80
Similarly,
Doing the same with tan20,tan30 and tan40,
We get,
Cot80.tan80.cot70.tan70.cot60.tan60.cot50.tan50
=1×1×1×1....... as tanA.cotA=1
=1