A plane, parallel to the center of the sphere, passes through the sphere at a distance of 20 cm from the center. The radius of the circular cross section is 15cm What is the radius of the sphere?

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle

4. (10.03 mc) the equation of line cd is y = −2x − 2. write an equation of a line parallel to line cd in slope-intercept form that contains point (4, 5). (4 points) y = −2x + 13 y = negative 1 over 2 x + 7 y = negative 1 over 2 x + 3 − 2x − 3

Titus works at a hotel. part of his job is to keep the complimentary pitcher of water at least half full and always with ice. when he starts his shift, the water level shows 4 gallons, or 128 cups of water. as the shift progresses, he records the level of the water every 10 minutes. after 2 hours, he uses a regression calculator to compute an equation for the decrease in water. his equation is w –0.414t + 129.549, where t is the number of minutes and w is the level of water. according to the equation, after about how many minutes would the water level be less than or equal to 64 cups?