Question

yadi tanA=15/8 tanB=7/24hai to cos(A+B)=?
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Answer 1

Answer:

87 / 425.

Step-by-step explanation:

See, cos(A + B) is basically cosAcosB - sinAsinB

So, if tan(A) = 15/8, then clearly sin(A) = 15/17, cos(A) = 8/17

Also, tan(B) = 7/24, so clearly sin(B) = 7/25 and cos(B) = 24/25

These are from simple trigonometric identities.

Then, cos(A+B) = (192 - 105)/425

Which makes it 87 / 425.