با توجه به رابطهٔ بالا، یعنی \({\sin ^2}\alpha + {\cos ^2}\alpha = 1\) جاهای خالی را پر کنید:
الف \({\sin ^2}\alpha + {\cos ^2}\alpha = 1\,\, \Rightarrow \;{\sin ^2}\alpha = ......\,\, \Rightarrow \;\sin \alpha = \pm \sqrt {\,...............\,} \)
ب \({\sin ^2}\alpha + {\cos ^2}\alpha = 1\,\, \Rightarrow \;{\cos ^2}\alpha = ......\,\, \Rightarrow \;\cos \alpha = \pm \sqrt {\,...............\,} \)
الف \({\sin ^2}\alpha + {\cos ^2}\alpha = 1\,\, \Rightarrow \;{\sin ^2}\alpha = 1 - {\cos ^2}\alpha \,\, \Rightarrow \;\sin \alpha = \pm \sqrt {1 - {{\cos }^2}\alpha } \)
ب \({\sin ^2}\alpha + {\cos ^2}\alpha = 1\,\, \Rightarrow \;{\cos ^2}\alpha = 1 - {\sin ^2}\alpha \,\, \Rightarrow \;\cos \alpha = \pm \sqrt {1 - {{\sin }^2}\alpha } \)