Changes
From Karnataka Open Educational Resources
344 bytes added
, 07:09, 11 July 2014
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− | #In Right angled ∆ABC,∟BAC= 90°,∟B: ∟C = 1:2 andAC= 4cm.calculate thelenght of BC | + | #1 In Right angled ∆ABC,∟BAC= 90°,∟B: ∟C = 1:2 andAC= 4cm.calculate thelenght of BC |
| ''''''Solution''''''''' | | ''''''Solution''''''''' |
| in some special right angled triangle | | in some special right angled triangle |
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| BC = 8 cm | | BC = 8 cm |
| | | |
− | #A door of width 6 mt has an archabove it having aheight of 2 mt , find the radius if the arch | + | #2 A door of width 6 mt has an archabove it having aheight of 2 mt , find the radius if the arch |
| + | |
| + | Solution |
| + | |
| + | In figure given |
| + | AB=6 mt width of door |
| + | CD=2 mt height of arch |
| + | let OC is radius of arch |
| + | OD= x mt |
| + | jion OB, |
| + | in ∆ODB ∟D= 90º |
| + | |
| + | <math>OB^2=OD^2+DB^2</math> |
| + | |
| + | <math>(x+2)^2=3^2+x^2</math> |
| + | |
| + | <math>4+4x+9=9+x^2</math> |
| + | |
| + | 4x=9-4 |
| + | |
| + | x=<math>\frac{5}{4}</math> |
| + | |
| + | x=1.25 |
| + | |
| + | But OC = 2+x |
| + | |
| + | OC= 2+1.25 |
| + | OC= 3.25 mt |
| + | radius of arch is 3.25 mt |
| + | |
| + | |
| # The sides of a right angled triangle are in an AP. Show that sides are in ther ratio 3:4:5 | | # The sides of a right angled triangle are in an AP. Show that sides are in ther ratio 3:4:5 |