WAEC - Mathematics (2003 - No. 40)
Evaluate Cos 45o Cos 30o - Sin 45o Sin 30o leaving the answer in surd form
\(\frac{\sqrt{2}-1}{2}\)
\(\frac{\sqrt{3}-\sqrt{2}}{4}\)
\(\frac{\sqrt{6}-\sqrt{2}}{2}\)
\(\frac{\sqrt{6}-\sqrt{2}}{4}\)
توضیح
\(cos45^o \times cos30^o - sin45^o \times sin30^o\\
\frac{1}{\sqrt{2}}\times \frac{\sqrt{3}}{2} - \frac{1}{\sqrt{2}}\times \frac{1}{2}\\
\frac{\sqrt{3}}{2\sqrt{2}}-\frac{1}{2\sqrt{2}}; = \frac{\sqrt{3}-1}{2\sqrt{2}}=\frac{\sqrt{6}-\sqrt{2}}{4}\)
\frac{1}{\sqrt{2}}\times \frac{\sqrt{3}}{2} - \frac{1}{\sqrt{2}}\times \frac{1}{2}\\
\frac{\sqrt{3}}{2\sqrt{2}}-\frac{1}{2\sqrt{2}}; = \frac{\sqrt{3}-1}{2\sqrt{2}}=\frac{\sqrt{6}-\sqrt{2}}{4}\)