Question

prove that a triangle must have at least two acute angles.

Answer 1

because the sum of triangle is 180 degree,that's why triangle have at least two acute angles

Answer 2

Case 1.
When ∆ is right angled triangle.
Then,
we have to prove that other two angle are acute.( let x and y )
So, x + y = 90°
we know that no angle can be zero.
So, x < 90°
or,
y < 90°
You can do the same by taking obtuse angled triangle.

Hope this may help you..

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