Let the function be
f( x )= sinax sinbx
We have to find the value of the function at Limit x→0
At a particular point at x=0 , the function takes the form of 0 0 .
We need to simplify the term to remove 0 0 form.
According to the trigonometric theorem,
lim x→0 sinx x =1 (1)
lim x→0 sinax sinbx = lim x→0 sinax lim x→0 sinbx (Applying limits to num and den)
On solving numerator and denominator separately we get,
lim x→0 sinax ax ⋅ax lim x→0 sinbx bx ⋅bx
As x→0 so ax→0,bx→0 thus from equation 1
f( x )= lim ax→0 sinax ax ⋅ax lim bx→0 sinbx bx ⋅bx = 1( ax ) 1( bx ) = a b
Thus the value of the given expression lim x→0 sinax sinbx = a b