a, b, c are the lengths of three sides of a triangle ABC. If a, b, c are related by the relation a2 + b2 + c2 = ab + bc + ca, then the value of sin2A+ sin2B + sin2C is
If sin 3A = cos (A - 26°), where 3A is an acute angle then the value of A is
29°
26°
23°
23°
A.
29°
sin 3A = cos (A - 26°).
⇒ cos (90° - 3A) = cos (A - 26°)
⇒ 90° - 3A = A - 26°
⇒ 90° + 26° = 3A + A
⇒ 4A = 116