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Prove that one interior angle of a a regular octagon = 135 degrees

Regular octagon has 6 triangles within it.

Total of interior angles in a triangle = 180 degrees

So the total of interior angles within a regular octagon would = 180 x 6 (=1080).

Answered by Acrisa K. • Maths tutor

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David travels from home to work at 30 mph. At the end of the day, he travels from work back home via the same route at 40 mph. What is his average speed while travelling? (Give your answer as a simplified fraction) (None-Calculator)

First set the distance between home and work as the value x miles.The time takento get from home to work is the value y hours.The time takento get from work to home is the value z hours.Then (as timeis eq...

Answered by David F. • Maths tutor

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y is proportional to x^2. When y=45, x=3. Find a formula for y in terms of x.

If y is proportional to x then you can write y=kx^2 where k is a constant you are trying to find. Then substitute in the values you have been given for x and y. This gives you 45=k(3)^2. Then work to solv...

Answered by Abbey P. • Maths tutor

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Expand (x + 4) (x - 8)

Multiply the first x term by the second x term (explain that any number times by itself is itself squared) = x^2Multiply the non-x term of the first bracket by the x term of the second bracket and check p...

Answered by Harry H. • Maths tutor

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The diagram shows the position of two ships, A and B, and a lighthouse L. Ship A is 5km from L on a bearing of 070° from L. Ship B is 3km from L on a bearing of 210° from L. Find the distance between A and B correct to 3.s.f.

(Draw diagram) From the diagram we can see that angle BLA= 210-70 = 140° . So for our triangle BLA we now have two sides and an included angle and we want to work out the length of the side opposite the a...

Answered by Callum S. • Maths tutor

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