- 58

- 0

13cos^2 - 5cos = 12sin^2 - 6

3) Scientists use visual magnitude to measure the brighness of a star. The smaller the number, the brighter the star. An increase in magnitude of 1 unit represents a decrease of 60% in the brighness of a star.

a) The star Vega has a magnitude of 0. If a second star has a visual magnitude of -2.4, how many times brighter than Vega is this star?

b) If a star is 15% as bright as Vega is , what is its visual magnitude?

c)How is this scale different from the Richter scale?

For this next question all I need is a basic run through of what I have to do.

4) a and B are both angles in the second quadrant. If sin a = 1/3 and sin B = 2/3, find the exact value of cos (a +b).

Thanks