Find m∠BFD. Show your steps and/or explain your reasoning.

If x-1 and x+3 are the factors of x3+10x2+ax+b find a and b

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?

Given sin28.4=.4756, cos28.4=.8796, and tan28.4=.5407 find the cos of 61.6