Question

if in a triangle ABC cos square A + cos square b + cos square C is equal to 1 then prove that triangle is right angled triangle​

Answer 1

Answer:

Step-by-step explanation:

If in a triangle ABC cos square A + cos square b + cos square C is equal to 1 then prove that triangle is right angled triangle​

Let say a triangle ABC is right angeled at ∠C

=> Cos²C = Cos²90 = 0

=> Cos²A + Cos²B + Cos²C = 1

=> Cos²A + Cos²B + 0 = 1

=>  Cos²A + Cos²B = 1

∠A + ∠B = 90°

=> ∠B = 90° -∠A

=> CosB = Cos(90° -∠A ) = SinA

=> Cos²A + Sin²A = 1

=> 1 = 1

Hence triangle is right angeled triangle

Answer 2

Answer:

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