question_answer

PQR is a triangle in which\[\angle \]PQR = \[\mathbf{90}{}^\circ \] and a perpendicular is drawn from Q to PR which intersects PR at S. If PQ = a, QR = b, PR = c and QS = p, then which one of the following is true?

A)  \[cp=ab\]          

B)                                            \[\frac{1}{{{p}^{2}}}=\frac{1}{{{a}^{2}}}+\frac{1}{{{b}^{2}}}\]

C)  \[\frac{1}{{{p}^{2}}}=\frac{1}{{{a}^{2}}}+\frac{1}{{{b}^{2}}}-\frac{1}{{{c}^{2}}}\]               

D)                    both A and B

E) None of these