we know that
1+cot ²∅=csc² ∅
cot ∅=4/7
so
1+(4/7)²=csc² ∅
csc² ∅=1+(16/49)
csc² ∅=(65/49)
csc ∅=(√65)/7
remember that
csc ∅=1/sin ∅
sin ∅=1/csc ∅------> sin ∅=7/√65-----> sin ∅=(7√65)/65
the answer is
the best identity to find sin ∅ is
1+cot ²∅=csc² ∅
