A geometry problem by Aakhyat Singh

Geometry Level 3

For a triangle Δ A B C \Delta ABC with angles A , B A, B and C C , if

cos ⁡ 2 A + cos ⁡ 2 B + cos ⁡ 2 C = 1 \cos^{2}A +\cos^{2}B + \cos^{2}C = 1

then Δ A B C \Delta ABC is a

Equilateral Isosceles Scalene Right angled triangle

Aakhyat Singh by Aakhyat Singh , 20, India

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2 solutions

Marta Reece
Jun 23, 2017

cos ⁡ 2 9 0 ∘ + cos ⁡ 2 x + cos ⁡ 2 ( 9 0 ∘ − x ) = 0 + cos ⁡ 2 x + sin ⁡ 2 x = 1 \cos^{2}90^\circ +\cos^{2}x + \cos^{2}(90^\circ-x) = 0+\cos^{2}x+\sin^{2}x =\boxed1

2 Helpful 1 Interesting 1 Brilliant 0 Confused
Hana Wehbi
Jun 23, 2017

It can also be right isosceles triangle.

1 Helpful 0 Interesting 0 Brilliant 0 Confused

It can be any right triangle

Edwin Gray - 2 years, 2 months ago

1 pending report

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