Problem

Manuel found that cos (2θ) = -7 and θ is not in the first quadrant. To remember it more easily, he wants to convert cos (2θ) into sin (θ). What is the value of sin (θ)?

(original post at @savvyplayer/may2021day1math 👈)

Answer

no solution 🎯

Solution

There is no angle which when inserted to a cosine function outputs a value of -7. It is because there is no triangle where one of the sides is 7 units while the hypotenuse is only 1 unit (from the identity cos (θ) = adjacent / hypotenuse), since the hypotenuse must be longer than both the legs of the right triangle.

(Sorry for the gritty graphics of my image made using Microsoft Paint) 😅

Winner: @minus-pi 🏅

1 HIVE has been sent to @minus-pi's Hive account. 💰

Nobody else has tried to submit their answer for the problem. 😮

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