secA - tanA = m then value of
secA^4-tanA^4-2secA
Answers
Step-by-step explanation:
If sec a - tan a = 4, then what is the value of cosec a?
sec a - tan a = 4 …(1). Let
sec a + tan a = m …(2)
Add (1) and (2)
2sec a = 4+m, or
sec a = (m/2) +2.
Subtract (1) from (2)
2tan a = m-4, or
tan a = (m/2) - 2
But 1 + tan^2 a = sec^2 a, or
1 + [(m/2) - 2]^2 = [(m/2) +2]^2, or
1 + 0.25m^2–2m+4 = 0.25m^2+2m+4, or
1 = 4m, or
m = 0.25
tan a = (m/2) - 2 = (0.25/2)-2 = -1.875
cot a = 1/(-1.875) = -0.533333
cosec a = [cosec^2 a]^0.5 = [1+cot^2 a]^2
= [ 1+(-0.533333)2]^0.5
= 1.28444444^0.5
cosec a = 1.1333333
Answer:
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Step-by-step explanation:
L.H.S
(1+tanA−secA)×(1+tanA+secA)
=(1+tanA)
2
−(secA)
2
[∵(a+b)(a−b)=a
2
−b
2
)]
=1+tan
2
A+2tanA−sec
2
A
=sec
2
A+2tanA−sec
2
A [∵sec
2
θ=1+tan
2
θ]
=2tanA
=R.H.S.
∴L.H.S=R.H.S
(1+tanA−secA)×(1+tanA+secA)=2tanA
Hence proved.