Step-by-step explanation:
Let a, b, c be the measures of the interior angles and x, y, z be the measures of the exterior angles of the triangle. Where x and adjacent to a, y is adjacent to b and z is adjacent to c.
By interior angle sum postulate of a triangle:
a + b + c = 180°... (1)
Therefore, by remote interior angle theorem:
x = b + c.... (2)
y = a + c..... (3)
z = a + b.... (4)
Adding equations (2), (3) & (4)
x + y + z = b + c + a + c + a + b
x + y + z = 2a + 2b + 2c
x + y + z = 2(a + b + c)... (5)
From equations (1) & (5)

Thus, the sum of exterior angles so formed is equal to four right angles.
Proved.
Answer: is there a question for/to the numbers gjven
The spider's movement is an illustration of a parabola.
- The equation of a parabola is:

- The focus of a parabola is: (40,-30)
- The axis of symmetry is:

- The directrix is:

<u>(a) The equation</u>
The spider passes through the origin.
So, we have:

The spider jumps to a maximum height of 10mm, midway 80mm.
So, the vertex is:

The equation of a parabola is:

So, we have:

Subtract 10 from both sides


Solve for a

Substitute
and
in 

<u>(b) The focus, directrix and the axis of symmetry</u>
The focus of a parabola is:

Where:

So, we have:



So, we have:


The axis of symmetry is:

So, we have:

The directrix is:



Read more about parabolas at:
brainly.com/question/25237745