Find the sum of the first 10 natural numbers using the sum formula: S = n/2 * (a + l), where n is the number of terms, a is the first term, and l is the last term.
+
What is the length of the third side if angle A is 30 degrees, angle B is 70 degrees, and side a = 5?
+
What is the limit of (x^2 + 2x - 1) / (x - 1) as x approaches 1?