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 个评论
Rik
2020-10-19
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
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
采纳的回答
Image Analyst
2020-10-16
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);
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/383233/image.png)
2 个评论
Image Analyst
2020-10-17
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.
更多回答(1 个)
meghannmarie
2020-10-16
编辑:meghannmarie
2020-10-16
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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