If r is the ratio of the roots of the equation x 2 − 5 x + 8 = 0 , then ( r + 1 )/2 r is equal to
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Step-by-step explanation:
MATHS
If in a △ABC,△=a
2
−(b−c)
2
, then tan A is equal to
Study later
ANSWER
Given:
Δ=a
2
−(b−c)
2
In a ΔABC:
Δ=
2
1
bcsinA
2
1
bcsinA=a
2
−(b−c)
2
2
1
bcsinA=a
2
−(b
2
+c
2
−2bc)
4
1
sinA=
2bc
−(b
2
+c
2
−a
2
)
+1
According to the Law of Cosines:
cosA=
2bc
−(b
2
+c
2
−a
2
)
4
1
sinA=−cosA+1
4
tanA
=−1+
1+(tanA)
2
1+(tanA)
2
=1+
16
(tanA)
2
+
2
tanA
tanA=0,
15
8
tanA
=0 [since ∠A
=0]
∴tanA=
15
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