A) 2
B) 3
C) 1
D) 4
Correct Answer: C
Solution :
(c): \[tan{{4}^{{}^\circ }}.tan{{43}^{{}^\circ }}.tan{{47}^{{}^\circ }}.tan{{86}^{{}^\circ }}\] \[=tan{{4}^{{}^\circ }}.tan{{43}^{{}^\circ }}.tan({{90}^{{}^\circ }}-{{43}^{{}^\circ }}).tan({{99}^{{}^\circ }}-{{4}^{{}^\circ }})\] \[=tan{{4}^{{}^\circ }}\times tan{{43}^{{}^\circ }}\times cot{{43}^{{}^\circ }}\times cot{{4}^{{}^\circ }}=1\] \[\left[ tan\left( {{99}^{{}^\circ }}-\theta \right)=cot\theta ;tan\theta .cot\theta =1 \right]\]You need to login to perform this action.
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