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in Trigonometry by (53.1k points)

In a ΔABC, sinA + sinB + sinC = 1 + √2 and cosA + cosB + cos B + cosC = √2 if the triangle is

(A)  equilateral 

(B)  isosceles 

(C)  right-angled 

(D)  right-angled isosceles

1 Answer

+1 vote
by (53.3k points)
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Best answer

Correct option (D)  right-angled isosceles

sinA + sinB + sinC = 1 + √2

and cosA + cosB + cos B + cosC = √2

Use odd one out rule

Take two angles π/4 and one angle π/2. This is satisfied.

B = π/2, A = C = π/4

Therefore, it is right-angled isosceles.

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