Question

Which trigonometry identities are most important for board exams?

Answer 1

Answer:

try memorizing all of the identities

Answer 2

Understand the way how the identities are derived and you would not have to learn them

Example

Sin^2 @+cos^2 @= 1

(This is the first basic/primary Pythagorean identity)

We know that,

Sin @ =opposite/hypotenuse

Cos @=adjacent/hypotenuse

In a right angled triangle

With reference to angle @
(Let it be any two angle except 90 degrees)

According to Pythagoras theorem

(Opposite side)^2 +(adjacent side )^2 =(hypotenuse)^2

Now,

Sin^2 @ +Cos^2 @
=(opposite /hypotenuse )^2 +(adjacent/hypotenuse)^2

=[(opposite)^2+(adjacent)^2]/(hypotenuse)^2

{since,according to Pythagoras theorem
(Opposite)^2 +(adjacent)^2 =(hypotenuse)^2}

=(hypotenuse)^2/(hypotenuse)^2

=1

Hence proved

Sorry for the inconvenience I have neither have special keyboard nor I know some tricks

If you understood what I taught then I would be very happy

Thankyou