allery$\sin(A + B) = $
A$\sin A + \sin B$
B$\sin A \cos B - \cos A \sin B$
C$\sin A \cos B + \cos A \sin B$
D$\cos A \cos B - \sin A \sin B$
Answer & Solution
Correct answer: C. $\sin A \cos B + \cos A \sin B$
Angle-sum formula for sine: $\sin(A + B) = \sin A \cos B + \cos A \sin B$.
Companion: $\sin(A - B) = \sin A \cos B - \cos A \sin B$ (option C — common trap, the sine of the *difference*).
For cosine: $\cos(A \pm B) = \cos A \cos B \mp \sin A \sin B$ (sign flips inside vs outside, option D is $\cos(A+B)$).
Sine is not linear in its argument: $\sin(A+B) \neq \sin A + \sin B$ generally.
Keep practising Quadratic Equations
Browse all Quadratic Equations questions for CBSE Class 10, or explore more Mathematics topics.
Related questions
Match each geometric word problem with its quadratic equation model:Match each relation between roots α, β of ax² + bx + c = 0 with its formula:Match each quadratic equation with its roots:Match each quadratic discriminant D = b² - 4ac value with the nature of roots:What does the discriminant tell you?True or false: quadratic equationsCLASS10 · Mathematics · Quadratic Discriminant — Gap FillQuadratic formula.