Question

If tana tanß = 1, then the value of cos(a + b) is
+
O – 1
O Zero
JE
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Answer 1

Answer:

tan a.tan b=1

then a=30°,b=60°

cos (a+b)=cos (30°+60°)

=cos (90°)

=0

Answer 2

The value of cos(α+ß) = 0

Given:

tan α tan ß = 1

To find:

The value of cos(α+ß) is

Solution:

Given tan α tan ß = 1

As we know tan 60 = √3 and tan 30 = 1/√3

⇒  tan 60 tan 30 = √3 × 1/√3  = 1

⇒  tan 60 tan 30 = 1

⇒ Take tan α = tan 60  ⇒ α = 60

⇒ Take tan ß = tan 30  ⇒ ß = 30

⇒ cos(α+ß) = cos(60+30) = cos 90 = 0

Therefore, the value of cos(α+ß) = 0

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