Question

∆ABC is a right-angled isosceles triangle, right-angled at C. Find cos A

Answer 1

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Answer 2

Step-by-step explanation:

Given : ∆ ABC is an isosceles ∆

thus, AC = CB

By phythagores theorem : AB*2 = AC*2 + BC*2

AB *2 = AC*2 + AC*2 = 2AC*2

AB = √ 2AC*2 = √2 AC

therefore, Cos A = B/H = AC / √2 AC = 1/ √2.

Ans : COS A = 1/√2.