Solution for sin6xcos4x dx?

I assume you want the integral?

Using your product-to-sum formula,
recall that sin6x cos4x = 1/2 (sin2x + sin10x)
Now the integral is easy.

To solve the integral of sin(6x)cos(4x) dx, we can use the double-angle formula for trigonometric functions, specifically the formula:

sin(A + B) = sinAcosB + cosAsinB

In this case, we have sin(6x)cos(4x), so we can rewrite it as:

2sin((6x + 4x) / 2)cos((6x - 4x) / 2)

Simplifying further, we get:

2sin(5x)cos(x)

Now, let's use the product-to-sum formula for trigonometric functions, which states:

sinAcosB = (1/2)(sin(A + B) + sin(A - B))

Applying this formula to our expression, we have:

2sin(5x)cos(x) = sin(5x + x) + sin(5x - x)

These can be further simplified as follows:

sin(5x + x) = sin(6x)

sin(5x - x) = sin(4x)

Therefore, the integral of sin(6x)cos(4x) dx can be written as:

∫(sin(6x)cos(4x)) dx = ∫(2sin(5x)cos(x)) dx

Simplifying further:

= ∫(sin(6x)) dx + ∫(sin(4x)) dx

Now, we can integrate each term separately:

Integrating sin(6x):

= -cos(6x) / 6

Integrating sin(4x):

= -cos(4x) / 4

Therefore, the solution to the integral ∫(sin(6x)cos(4x)) dx is:

= -cos(6x) / 6 - cos(4x) / 4 + C

where C is the constant of integration.