Cos^2a + cos^2b +cos^2c +2cosacosbcosc= 1

Answer this question only if you know the 30 points and

If the scale factor between two circles is 2x/5y what is the ratio of their areas?

Someone answer asap for ! the following statements are true about the coins calvin and sasha have collected. * calvin and sasha has the same amount of money. * calvin has only quarters. * sasha has dimes, nickels, and pennies * calvin has the same number of quarters as sasha has dimes. * sasha has $1.95 in coins that are not dimes. exactly how many quarters does calvin have?