Rock B.

asked • 11/22/17

Trigonometry

prove that
(1-tan26)(1-tan266)= -4

1 Expert Answer

By:

Arturo O. answered • 11/22/17

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Has it occurred to you to just evaluate the expression on the left hand side, and see if it gives -4?   Try it.
 
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Rock B.

yes, i tried that. but i did not get -4 .we are not allowed to directly input the value of tan 6 and tan 66. 
the actual question is:
tan6.tan42.tan66.tan78=1
 
i reached here while solving from left hand side.
(-1/4) (1-tan26)(1-tan266)
the calculator too shows that it is -4.
and i know i am a few steps away.
 
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11/22/17

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