question_answer

Find the value of \[\mathbf{Co}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{0}{}^\circ \text{ }+\text{ }\mathbf{Co}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{5}{}^\circ \text{ }+\]\[\mathbf{Co}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{10}{}^\circ \text{ }+\text{ }\mathbf{Co}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{15}{}^\circ \text{ }+\_\_\_\_+\text{ }\mathbf{Co}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{90}{}^\circ \]

A)  5                                                                    

B)  7           

C)  10                   

D) 9

E) None of these