Verify that sin(A+B) + sin(A-B) = 2sinA sinB ?

Question

Verify that sin(A+B) + sin(A-B) = 2sinA sinB ?

2 Answers

Impact of this question

2092 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-04-14T19:45:42

$"see explanation"$

Explanation:

$"using the "color(blue)"addition formulae for sin"$

$•color(white)(x)sin(A+-B)=sinAcosB+-cosAsinB$

$rArrsin(A+B)=sinAcosB+cosAsinB$

$rArrsin(A-B)=sinAcosB-cosAsinB$

$rArrsin(A+B)+sin(A-B)=2sinAcosB$

$!=2sinAsinBlarr"check your question"$

Answer 2 · 2018-04-14T19:50:34

It is not an identity.

Explanation:

It is not an identity.

$A = 90° , B = 0°$
LS: $sin(A+B) + sin(A-B) = sin (90°+0°) + sin ( 90°-0°) = 2$
RS: $2sinA sinB = 2 sin 90° sin 0° = 2 xx1xx0 = 0$
$2!=0$

$= 2sinA sinB$

$sin(A+B) + sin(A-B) = 2sinA sinB$

$LHS: sin(A+B) + sin(A-B)$

$sinAcosB + cosAsinB + sinAcosB - cosAsinB =$

$sinAcosB + sinAcosB = 2sinAcosB$

Science

Math

Humanities

... and beyond

Verify that sin(A+B) + sin(A-B) = 2sinA sinB ?

2 Answers

Explanation:

Explanation:

Related questions

Impact of this question