We know, cos A + cos B = 2cos(C+D)/2 × cos(C - D)/2
So,
cos 130 + cos 110 + cos 10
cos 130 + 2cos (110+10)/2 × cos( 110-10)/2
cos 130 + 2cos 60 × cos 50
cos ( 180 - 50 ) + 2cos60 cos 50
We know, cos ( 180 - A ) = -cos A
2cos 60 cos 50 - cos 50
Also, cos 60 = 0.5
2×0.5 cos 50 - cos50
cos 50 - cos 50
0 = RHS.
Hence proved
Answer:
14
Step-by-step explanation:
You add 50 and 26 together to get 76, then you subtract 90 and 76 to get 14
Step-by-step explanation:
Geometric mean is the square root of the product.
√(9 × 11) = √99 ≈ 9.950
Answer: x=0.4
Step-by-step explanation:
0.5x + 4+0.9x = x+5
1.4x-x= +1
0.4x=1
X=0.4
Hope this helps
