Mark the tick against the correct answer in the following:
To find: Value of
Formula used: (i)
We have,
On expanding the above,
⇒ {cos 70°} {cos 20°} – {sin 70°} {sin 20°}
On applying formula
⇒ {sin (90 – 70)} {sin (90 – 20)} - {sin 70°} {sin 20°}
⇒ {sin 20°} {sin 70°} - {sin 70°} {sin 20°}
= 0