I have a task where I have to calculate the area of a triangle from degrees 1 to 90, that is bound within a semi circle. I keep getting an error with the last line for some reason
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I have a task where I have to calculate the area of a triangle from degrees 1 to 90, that is bound within a semi circle. I keep getting an error with the last line for some reason.
radius = rand;
a = 2*radius;
alpha = (1:90)
b = a * cosd(alpha(1:90));
area = 0.5*a*sind(1:90)
triangle= area*b
2 Comments
Accepted Answer
Image Analyst
on 16 Oct 2020
You need to be using .* instead of * to do an elemenet by element multiplication instead of a matrix multiplication. Try this:
radius = 2 * rand;
alpha = (1:90)
bases = radius * cosd(alpha) % A vector of 90 elements
heights = radius * sind(alpha) % A vector of 90 elements
triangle_areas = 0.5 * bases .* heights % A vector of 90 elements
% For optional fun, plot the area.
plot(alpha, triangle_areas, 'b.-', 'LineWidth', 2);
grid on;
xlabel('Angle', 'FontSize', 18);
ylabel('Area', 'FontSize', 18);
title('Triangle Area vs. Angle', 'FontSize', 18);

2 Comments
Image Analyst
on 17 Oct 2020
You can Accept only one answer, so accept the best one. However you can also vote for that and the other(s) to award those persons additional reputation points also.
More Answers (1)
meghannmarie
on 16 Oct 2020
Edited: meghannmarie
on 16 Oct 2020
You need to use the dot operator if you are doing element wise multiplication (.*). You use just the asterick for matrix multiplication.
triangle= area.*b
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