sin² 180/18 + sin²180/9 + sin² 7X180/18 + sin²4 X 180/9 = 2
prove it
Question from book R.D Sharma Class-XI of chapter: Trigonometric functions..
plz help me
2007-11-06 16:14:26 · 3 answers · asked by Amar 2 in Science & Mathematics ➔ Mathematics
sin 7x180/18 = sin(9x180/18 - 2x180/18) = sin(90 - 180/9) = cos(180/9)
sin² 7X180/18 = cos² 180/9
sin 4x180/9 = sin(9x180/18 - 180/18) = sin(90 - 180/18) = cos(180/18)
sin² 4X180/9 = cos² 180/18
sin² 180/18 + sin²180/9 + sin² 7X180/18 + sin²4 X 180/9 = sin² 180/18 + sin²180/9 + cos² 180/9 + cos² 180/18
= (sin² 180/18 + cos² 180/18) + (sin²180/9 + cos² 180/9) = 1 + 1 = 2
2007-11-06 16:34:12 · answer #1 · answered by zsm28 5 · 1⤊ 0⤋
sin² 180/18 + sin²180/9 + sin² 7X180/18 + sin²4 X 180/9 =? 2
sin² 10 + sin² 20 + cos² 20 + cos² 10 =? 2
sin² 10 + cos² 10 + sin² 20 + cos² 20 =? 2
1 + 1 = 2
2007-11-06 16:35:05 · answer #2 · answered by Helmut 7 · 0⤊ 0⤋
Wow! I am sorry but in the time it took you to type and post all TEN questions you could have solicited help in just one an then applied the same rules to the other nine. All of these questions deal with simple triangles. Regardless of if it is a shadow cast by the sun (a triangle from the tip of the pole to the end of the shadow) or the width of a stream ( a triangle laid on it side), they use virtually the same technique to solve. By asking for SOLUTIONS rather then the way the problem is solved, you will only learn to ask for help.. not how to solve your own problems. Sorry, again but I think what you really should do is to rethink what you want to accomplish .
2016-05-28 05:36:27 · answer #3 · answered by syreeta 3 · 0⤊ 0⤋