Question 476393
 {{{(sin B + cos B) (sin B - cos B) = 2 (sin( B))^2- 1}}}
Use formula {{{(a+b)(a-b)=a^2-b^2}}}
{{{(sin B + cos B) (sin B - cos B) =(sinB)^2-(cosB)^2}}}
Use formula {{{(sinB)^2+(cosB)^2=1}}} => {{{(cosB)^2=1-(sinB)^2}}}
{{{(sin B + cos B) (sin B - cos B) =(sinB)^2-(cosB)^2=(sinB)^2-(1-(sinB)^2)=(sin B)^2-1+(sinB)^2 =2 (sin B)^2- 1}}}