Ask Singapore Homework?

Upload a photo of a Singapore homework and someone will email you the solution for free.



Question

secondary 3 | E Maths
2 Answers Below

Anyone can contribute an answer, even non-tutors.

Answer This Question
Alex
Alex

secondary 3 chevron_right E Maths chevron_right Singapore

Help

Date Posted: 4 years ago
Views: 622
Eric Nicholas K
Eric Nicholas K
4 years ago
(8, 4) is directly to the right of (3, 4).
(3, 1) is directly below (3, 4).

This means that the triangle will contain one horizontal line and one vertical line, and as we know it too well, any horizontal line meets any vertical line at right angles.

The position of the right angle is at (3, 4), which is point P.

For the shortest distance from P to QR, the line drawn from P must touch line QR at a random point S such that PS is perpendicular to QR.

Now, the area of the triangle can be calculated in two different ways, but both obviously give the same area.

Firstly, we can use 0.5 * PQ * PR, which is 0.5 * 3 * 5 = 7.5 units2.

Secondly, we can use 0.5 * QR * PS, which will also give 7.5 units2.

As such,

0.5 * QR * PS = 7.5
QR * PS = 15

Since QR is the hypotenuse of the right angled triangle PQR, we use the Pythagorean Theorem

“a2 + b2 = c2”

to find the length QR. Of course, QR is the square root of (3^2 + 5^2), or the square root of 34.

As such,

PS = 15 / QR
PS = 15 / sqrt 34

I have no calculator for this.
Alex
Alex
4 years ago
what does this * stands for ?
Eric Nicholas K
Eric Nicholas K
4 years ago
The multiplication symbol; using the symbol “x” may create confusion as the multiplication sign “x” and the alphabet “x” may appear similar.
Alex
Alex
4 years ago
How did u get 0.5 and what does ^ stands for
Eric Nicholas K
Eric Nicholas K
4 years ago
Area of a triangle is 1/2 * base * height, which I write as 0.5 instead.

“^” is the symbol for power, as I do not have the specialised tools to write an actual power. “3^2” means 3 raised to the power of 2 (which equals 9), while “4^3” means 4 raised to the power of 3 (which equals 64).
Eric Nicholas K
Eric Nicholas K
4 years ago
The most important part in this question is to realise that the shortest path from a point to a line is a direct run to the straight line, so that the path taken is perpendicular to the line.
Alex
Alex
4 years ago
Thank you !!

See 2 Answers

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Phoebelyn Gwee
Phoebelyn Gwee's answer
5 answers (Tutor Details)
1st
Not sure if im right. Use converse of pythagoras thm.. and compare area to find perpendicular height.
Matthew Fan
Matthew Fan
4 years ago
5^2+3^2 is not quite as big as 40. Also on the third last line, I believe you meant 1/2*5*3
done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Matthew Fan
Matthew Fan's answer
9 answers (Tutor Details)