Sure, I can help simplify this expression.

1-4sin10sin70/2sin10
= 1 - 4(sin10)(sin70) / (2sin10)
= 1 - 2(sin70)
= 1 - 2(sin(90-20))
= 1 - 2(cos20)
= 1 - 2cos20

Now let's simplify the other expression:

sin(a+40) - cos(a)sin40 / cos(a)cos40

Combining the terms with "cos(a)", we get:

= sin(a+40) / cos(a) - cos40sin(a) / cos40
= tan(a+40) - tan(a)

So the simplified expression is:

1 - 2cos20 - (tan(a+40) - tan(a))