Question

If sin (2x) = cos (7x), then what is the value of x

Answer 1

we know that

if sin (2x) = cos (7x)
then
(2x) and (7x) are complementary angles
so
(2x)+(7x)=90----------> 9x=90-------> x=90/9--------> x=10°

the answer is
x=10°