Please could you help me with two questions?

 These are the numbers in the triangular number sequence

The next number in the sequence is 21.

Step-by-step explanation:

This is very hard to explain in words, so here is a very helpful site: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiY49vZ89HqAhVVg3IEHYhvBOEQFjABegQIDBAD&url=https%3A%2F%2Fwww.mathsisfun.com%2Falgebra%2Ftriangular-numbers.html%23%3A~%3Atext%3DTriangular%2520Number%2520Sequence-%2CTriangular%2520Number%2520Sequence%2C36%252C%252045%252C%2520...&usg=AOvVaw2VaSKvp44XlMUMBHxX-7Jj

Hope it helps <3

something that characterises a right triangle is the fact that we may use pythagoras' theorem to find any one of its sides given that we have the length of the other two sides. here, we have the length of the hypotenuse, √(87) yd, and one other side, √(23) yd, thus we can easily find the length of the remaining side using pythagoras' theorem as defined below:

c^2 = a^2 + b^2, where c is the length of the hypotenuse, and a and b are the lengths of the other two sides.

thus, given that c = √(87) and a = √(23), we may substitute these into the formula we defined above to get:

c^2 = a^2 + b^2

(√87)^2 = (√23)^2 + b^2 (substitute c = √87 and a = √23 into the equation)

87 = 23 + b^2 (evaluate (√87)^2 = 87 and (√23)^2 = 23 - remember that the square root of a number, squared will equal that very same number)

64 = b^2 (subtract 23 from both sides)

√64 = b (take the square root of both sides)

8 = b (evaluate √64 = 8)

therefor, the length of the unknown leg in the right triangle is 8 yd (first answer).

step-by-step explanation:

this is not possible to solve with the info given.   you need at least an one angle somewhere.