I need help on this test question help me please :)

1. if events a and b are non-overlapping events, how do you find the probability that one or the other occurs? 2. what does it mean if p(a or b) equals 1?

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given

Circle a has center of (2,3) and a radius of 5 and circle b has a center of (1,4) and a radius of 10. what steps will show that circle a is similar to circle b 1) dilate circle a by a scale factor of 2 2) translate circle a using the rule (x+1,y-1) 3) rotate circle a 180 degrees about the center 4) reflect circle a over the y-axis