Andijon davlat pedagogika instituti “Aniq va tabiiy fanlar” fakulteti

sin2a=sin(a+a)=sina*cosa+cosa*sina=2sina*cosa;
cos2a=cos(a+a)=cosa*cosa-sina*sina=cos²a-sin²a;
Endi shu formulalarga ko’ra misollarni ishlaymiz
Hisoblang:
1)2sin15°cos15°=sin(2*15°)=sin30°=
2)cos²15°-sin²15°=cos30°=
3)(cos75°-sin75°)²=cos²75°-2sin75°cos75°+sin²75° = sin²75°+cos²75°-sin150°=1-
4)(sin15°+cos15°)² = sin²15°+2sin15°cos15°+cos²15°=1+
5)2
6)cos² – sin² = cos =
7)
8)
Ifodani soddalashtring :
1)
2)
3)
4)sin2a + (sina-cosa)²= 2sinacosa+sin²a-2sinacosa+cos²a= 1;
5. Darsni yakunlash va darsda yaxshi qatnashgan o`quvchilarni rag`batlantirish.
O`quvchilarning olgan baholarini jurnalga va kundalikka qo`yish.
6. Uyga vazifa
Ifodani soddalashtring:

1. 
   2cos²15° - 1 =2cos²15° - sin²15° - cos²15° = -sin²15°+cos²15° = cos30° =
   
2. 
   1-2sin²22,5° = sin²22,5°+cos²22,5° - 2sin²22,5° = cos²22,5° - sin²22,5°= cos45° =
   
3. 
   
   
4. 
   
   

Aniyatni isbotlang :
1) 1 + cos2a = 2cos²a;
sin²a+cos²a+cos²a-sin²a=cos²a+cos²a=2cos²a;
2) 1-cos2a=2sin²a;
sin²a+cos²a-cos²a+sin²a= sin²a+sin²a=2sin²a;