Maths help (1 Viewer)

[highshill]

give the exact value for sin(-225)
i am getting sq root 3 / 2 but answer is 1/sq root 2
Why

 

[InteGrand]

give the exact value for sin(-225)
i am getting sq root 3 / 2 but answer is 1/sq root 2
Why

Note

sin(-225 deg) = -sin(225 deg) (sin is odd)

= -sin((180-225) deg) (recall the identity sin(180 deg – X) = sin X)

= -sin(-45 deg)

= sin(45 deg)

= 1/(sqrt(2)).

 

[highshill]

so when do i apply these identities

 

[InteGrand]

so when do i apply these identities

You can use them to get the given angle down to a number that you known the exact trig. value of.

 

[highshill]

like my book does not use it, but the answers are a following that identity have i understood the concept wrong

 

[InteGrand]

like my book does not use it, but the answers are a following that identity have i understood the concept wrong

Is it Maths In Focus?

 

[highshill]

yes

 

[Esse]

is it maths in focus?

hhahahahha