Final answer:
To multiply sin(40 degrees) by sin(20 degrees), one would generally use a calculator or a trigonometric table to find the exact values and then multiply them. The provided reference information does not contain an identity for directly calculating the product of two sines of different angles.
Step-by-step explanation:
The question involves multiplying two trigonometric functions, specifically sin(40 degrees) by sin(20 degrees). There isn't a straightforward formula for the product of sines of two different angles, but if this were a sum rather than a product, trigonometric identities such as the sine of a sum could potentially be useful. Unfortunately, the provided reference information does not offer a direct method for calculating the product of sin(40 degrees) and sin(20 degrees).
To solve the problem accurately, you would typically either use the values from a trigonometric table or a calculator to obtain the numerical values of sin(40 degrees) and sin(20 degrees) and then multiply them together. Therefore, without the exact values or additional relevant identities, the multiplication requested cannot be satisfactorily performed with the given information.