Question

find the value of A when cos 2A=sin3A​

Answer 1

Answer :-

• 18°

Given :-

• cos2A = sin3A

To Find :

• Value of A.

Formula used :-

• cos = (90° - sinA)

Solution :-

cos2A = sin3A

→ sin (90° - 2A) = sin3A

→ 90° - 2A = 3A

→ 90° = 3A + 2A

→ 90° = 5A

→ A = 90°/5

→ A = 18°

Hence, the value of A is 18°.

More To Know :-

• sin (90° - A) = cosA

• tan (90° - A) = cotA

• cot (90° - A) = tanA

• sec (90° - A) = cosecA

• cosec (90° - A) = secA

Answer 2

Answer :

Given :

• 2A = sin3A

To Find :

• Value of A

Solution :

$\:\:\:\:\:\:\leadsto \sf{cos \theta \:=\: sin (90°\:-\: \theta)}$

➪ $\sf sin(90°\:-\:2A)\:=\:sin3A$

➪ $\sf 90°\:-\:2A\:=\:3A$

➪ $\sf 90° \:=\: 3A\:+\:2A$

➪ $\sf 90° \:=\: 5A$

➪ $\sf A\:=\: \dfrac{90°}{5}$

➪ $\sf A\:=\:18°$

• Value of A is 18°

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