Find the exact value of cos A in simplest radical form. ​

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

[15 points]find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible

In need of in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.