Plz help with this problem

In δabc, m∠acb = 90°, cd ⊥ ab and m∠acd = 45°. find: a find cd, if bc = 3 in

Can someone me with my math problems i have a bunch. i will give brainliest and lots of pleeeaaasssee

Ameteorologist is studying the monthly rainfall in a section of the brazilian rainforest. she recorded the monthly rainfall, in inches, for last year. they were: 10.4, 10.3, 11.7, 11.1, 8.0, 4.4, 2.6, 1.8, 2.5, 4.4, 7.3, 9.5 fill in the missing values in the formula. what is the variance?