21). To ensure that the two triangle ABC and DEF are congruent, the three conditions given below : AB=DE, AC=DF and \( \Large \angle ABC = \angle DEF \) are
| A). sufficient but not necessary |
| B). necessary but not sufficient |
| C). neither necessary nor sufficient |
| D). both necessary as well as sufficient |
|
22). If D is a point on the side AB of \( \Large \triangle ABC \) and DE is a line through D meeting AC at E such that \( \Large \angle ADE = \angle ACB \), then AB AD is equal to
| A). AE . BC |
| B). AC . DE |
| C). AE . AC |
| D). AB . BC |
|
23). D, E, F are mid points of BC, CA AB of \( \Large \triangle ABC \). If AD and BE intersect in G, then AG + BG + CG is equal to
| A). AD = BE = CF |
| B). \( \Large \frac{2}{3} \) (AD+BE+CF) |
| C). \( \Large \frac{3}{2} \) (AD+BE+CF) |
| D). \( \Large \frac{1}{3} \) (AD+BE+CF) |
|
