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Need help on maths sheet!

Is anyone willing to help me answer the following question. I find it really hard and am struggling. Hope someone has time to help!92AF02A1-F82E-4B14-9EA2-59ED5E3FCD5C.jpg.jpeg
(edited 6 years ago)
Original post by Studentttt101
Is anyone willing to help me answer the following question. I find it really hard and am struggling. Hope someone has time to help!92AF02A1-F82E-4B14-9EA2-59ED5E3FCD5C.jpg.jpeg


The diagonals of a rhombus intersect at right angles.

Gradient of DB is?

Hence gradient of AC is?

And it goes through A, so its equation is?
I don’t really get what you mean. Do you know how to work it out or the answer?
Original post by Studentttt101
I don’t really get what you mean. Do you know how to work it out or the answer?


We don't do questions for you - you've been given hints.
I had this question on a practise paper. I can’t answer it for you - however, if you join points A and C you get an X shape, splitting the rhombus into 4 triangles. The angles in the X will all be 90°, adding up to the standard 360°. You can use that.
Isnt the answer meant to be an equation not an angle?
Original post by Studentttt101
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What I gave you are the steps required to solve the problem.

You should know that if two lines intersect at right angles then the product of their gradients is -1. You also should know how to find the equation of a line, given a point on it and its gradient.
You use y = mx+ c?
Original post by Studentttt101
You use y = mx+ c?


That's one way. Just substitute the point A's coordinates for x,y and knowing m, you can work out c. Done.
Original post by Studentttt101
You use y = mx+ c?


This is something you don't seem to know but need to remember:
All the points on a line satisfy its equation.

The reverse of this can be used to discover a yy-intercept using its gradient and a point on it.

if y=mx+cy=mx+c, c=y−mxc = y-mx. Therefore if you know a point (a,b)(a, b) on the line, c=b−mac=b-ma.
Hence, you have worked out the equation of the line.

To solve this equation find mm and then use what I explained to work out cc. The diagonals of a rhomus perpendicularly intersect.

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