Question

1-cos 20 19. HW If = 30°, verify that (i) cos 30 = 4 cos 0-3 cos 0 (ii) sin 0=root 1 - cos 2 tetha/2 ​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

cos(3×30°)=4cos^3(30°)-3cos(30°)

cos 90°=4cos^3(30°)-3cos(30°)

0=4(_/3÷2)^3-3×_/3÷2

0=(12_/3)/8-(3_/3)/2

0=(3_/3)/2-(3_/3)/2

0=0

b) sin(3×30°)=3sin(30°)-4sin^3(30°)

1=3×1/2 - 4×1/8

1=3/2-1/2

1=2/2

1=1