Question

if a=b=45°,show that sin(a-b)=sin a cos b-cos a sin b​

Answer 1

"sin (A-B) = sinA cosB - cosA sinB"

"cos (A-B) = cosA cosB + sinA sin B"

To find:

The value of

Answer:

Given that

Sin (A-B) =SinA CosB - CosA SinB

Cos (A-B) =CosA CosB + SinA SinB

We need to find the

Answer 2

Answer:

A/Q,a=b=45°

than ,put the value if a and b,

LHS:-sin(a-b)

sin(45°-45°)

=sin0°=0

now,

RHS:-sina cosb - cosa sinb

again,put value,a and b

sin45°cos45°-cos45°sin45°

,intersect each other=0

or ,

sin45°=1/√2,

cos45°1/√2

,thus 1/√2×1/√2-1/√2×1/√2

1/2-1/2=0

thus ,

LHS=RHS=0