1. Determine if each of the following triangles is a right-angled triangle. For each right-angled triangle, state the right angle. (Check attached picture) The answers are:
(a) Yes; <B
(b) No
(c) No
(d) Yes; <O

I want to know how these answers came, like how can we determine if the triangle is a right-angled triangle or not and which angle is the right angle from the statements in the question. ​

Suppose there is a simple index of three stocks, stock abc, stock xyz, and stock qrs. stock abc opens on day 1 with 4000 shares at $3.15 per share. stock xyz opens on day 1 with 5000 shares at $4.30 per share. stock qrs opens on day 1 with 6000 shares at $4.60 per share. the price of stock abc on day 8 begins at $3.50. the price of stock xyz on day 8 begins at $3.90. stock qrs opens on day 8 with a price of $4.50 per share. assume that each stock has the same number of shares that it opened with on day 1. what is the rate of change of this simple index over 1 week?

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.

One positive integer is 2 less than another. the product of the two integers is 24. what are the integers?