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If ∠J and ∠K are acute angles in a right triangle and m∠J is less than 60°, then cos(J)=cos(K)

User ChrisV
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In a right triangle, the sum of the measures of the two acute angles is always 90 degrees. So if ∠J and ∠K are acute angles in a right triangle, then we have:

m∠J + m∠K = 90°

Since m∠J is less than 60°, it follows that m∠K is greater than 30°, because their sum is 90°.

Now, let's consider the cosine of ∠J and ∠K. By definition, the cosine of an angle in a right triangle is the ratio of the adjacent side to the hypotenuse. So we have:

cos(J) = adjacent side to ∠J / hypotenuse

cos(K) = adjacent side to ∠K / hypotenuse

Since ∠J and ∠K are acute angles in a right triangle, they each have a unique adjacent side. Since the triangle is a right triangle, the hypotenuse is always the same, regardless of which angle is being considered.

Therefore, in general, it is not true that cos(J) = cos(K) for all right triangles with acute angles ∠J and ∠K, where m∠J is less than 60°. It depends on the specific values of the adjacent sides.

User Alamakanambra
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