The value of tan(7 1/2) is equal to sqrt(6)+sqrt(3)+sqrt(2)-2, sqrt(6)-sqrt(3)+sqrt(2)-2 ,sqrt(6)-sqrt(3)+sqrt(2)+2, sqrt(6)-sqrt(3)-sqrt(2)-2

saussito5cl

saussito5cl

Answered question

2023-02-12

The value of tan712° is equal to A6+3+2-2 B6-3+2-2 C6-3+2+2 D6-3-2-2

Answer & Explanation

veitigaq

veitigaq

Beginner2023-02-13Added 5 answers

The true option is B 6-3+2-2
Explanation for the correct option
The given trigonometric expression: tan712°.
It is known that sin(A-B)=sin(A)cos(B)-cos(A)sin(B).
Therefore, sin15°=sin45°-30°
sin15°=sin45°cos30°-cos45°sin30°sin15°=12×32-12×12sin15°=322-122sin15°=3-122sin15°=223-1222sin15°=26-28sin15°=6-24
It is known that cos(A-B)=cos(A)cos(B)+sin(A)sin(B).
Thus, cos15°=cos45°-30°
cos15°=cos45°cos30°+sin45°sin30°cos15°=12×32+12×12cos15°=322+122cos15°=3+122cos15°=223+1222cos15°=26+28cos15°=6+24
Now, tanA=sinAcosA.
tanA=2sinAcosA2cos2AtanA=sin2A1+cos2A
Thus, tan712°=sin15°1+cos15°.
tan712°=6-241+6+24tan712°=6-24+6+2tan712°=6-24-6+24+6+24-6+2tan712°=46-2-6-26+216-6+22tan712°=46-42-6+216-6-2-212tan712°=46-42-48-43tan712°=6-2-12-3tan712°=6-2-12+32-32+3tan712°=26-22-2+18-6-34-3tan712°=6-22-2+32-3tan712°=6-3+2-2
Hence, option B is correct.

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