Which biconditional statement is not true? a)two lines are perpendicular if and only if they intersect to form right angles. b)a triangle is a right triangle if and only if the lengths of its sides are related by the equation a2+b2=c2. c)a quadrilateral is a rectangle if and only if it has exactly four right angles. d)a triangle is equilateral if and only if it has three sides

If (a, b) is the solution to the system of equations shown above, and a and b are integers, then what is the value of a+b?

Anna’s mother prepares sauerkraut, a fermented dish made from finely cut cabbage and salt. lactobacillus bacteria present on the surface of the cabbage combine with salt to turn the cabbage into a crunchy, sour dish. what chemical process occurs to create this dish? a. alcoholic fermentation b. cellular respiration c. conservation d. lactic acid fermentation e. photosynthesis

Scientists observed a rock stratum with fossil. if mollusks evolved before arthropod, where will their fossils be found.