Question

Find the value of A if:
sin 3A = cos (A - 26°), where 3A and A - 26° are acute angles,
Solution. Given sin 3A = cos (A - 26°)
cos (90° - 3A) = cos (A - 26°)
90° – 3A = A - 26°
(3A is an acute angle, so 90° - 3A is an acute angle, also A - 26° is an acute angle)
116° = 4A = A= 29º.
Hence, the value of A is 29º.

please explain the line......(3A is an acute angle, so 90° - 3A is an acute angle, also A - 26° is an acute angle) !​

Answer 1

Answer:

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