Elitmus
Exam
Numerical Ability
Trigonometry
If a = tan6 tan 42
and B = cot66 cot 78
then
(a) A = 2B (b)
1
AB
3
=
(c) A = B (d) 3A = 2B.
Read Solution (Total 5)
-
- a=tan6 tan42
b=cot66 cot78 can be written as tan24 tan12 bec cot(90-t)=tant;
tanA tanB = tanC tanD if A+B=C+D; or A+B =C-D or A-B=C+D or A-B=C-D;
as 42-6=24+12;
both are equal. - 12 years agoHelpfull: Yes(34) No(5)
- c) A = B
If A = tan6 tan 42 and B = cot66 cot 78 then,
A/B = 1. So, A =B - 12 years agoHelpfull: Yes(16) No(7)
- value of tan6tan42=-0.67
and cot66cot78=-1.005
so,3A=2B is rd. answer - 11 years agoHelpfull: Yes(4) No(17)
- We know that tanx*tan(60-x)*tan(60+x)=tan3x
now A/B=tan6.tan42.tan66.tan78
- 9 years agoHelpfull: Yes(1) No(0)
- A=tan6°tan42° and B=cot66°cot78°
A/B=tan6°tan42°tan66°tan78°
Using tan(60-x)tanxtan(60+x)=tan3x for x=18° we get
tan42°tan18°tan78°=tan54°...(1)
for x=6° we get
tan54°tan6°tan66°=tan18°...(2)
Eliminating tan54°between (1) and (2)
we get
tan6°tan42°tan66°tan78°=1
Hence A/B=1. - 7 years agoHelpfull: Yes(1) No(0)
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