Question

find the value of sin21 by cos69​

Answer 1

Step-by-step explanation:

the value is 1

sin 21 /cos69

sin 21/ cos (90-21)

sin 21/ sin21

therefore the answer is 1

Answer 2

Answer:

Trigonometric Identity:

Sin Ф = Cos ( 90 - Ф )

Here, Ф represents Theta or the angle in degrees.

According to your question, we have to find Sin 21° divided by Cos 69°.

According to the above mentioned trigonometric identity, we can change the value of Sine angle in terms of Cos Angle. Hence,

→ Sin 21° = Cos ( 90° - 21° )

→ Sin 21° = Cos ( 69° )

Hence substituting Sin 21° as Cos 69°, we get:

$\rightarrow \dfrac{Sin \:21^\circ}{Cos\: 69^\circ}\\\\\\\rightarrow \dfrac{ Cos\:69^\circ}{Cos\:69^\circ} \implies 1$

Therefore the value of Sin 21° by Cos 69° is 1.