> For the complete documentation index, see [llms.txt](https://help.prequilt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.prequilt.com/prequilt-101/build-a-block-unit-for-the-fabric-calculator/triangular-units/triangle-in-a-square-tri-rec.md).

# Triangle in a Square (Tri Rec)

<figure><img src="/files/axSbiphUF5ycw99CDTNA" alt="" width="375"><figcaption><p>Triangle in a Square Block Unit</p></figcaption></figure>

## <mark style="color:blue;">Triangle in a Square (Tri Rec) Block Unit in PreQuilt</mark>

This more intermediate or advanced block unit can be tough to nail in the sewing room. But it's pretty easy peasy in PreQuilt.

**Triangle in a Square** block units are constructed using one isosceles triangle with a half rectangle triangle on either side of it. Overall, these three shapes within the overall square shape.

This shape is also sometimes referred to as a **Tri Rec** (and if you know why, please let me know!).

And since the idea behind this series is to build a block unit that can be used to create a larger block,  I'm going to create a 12" finished block that has Triangle in a Square block units in it (like for example, the **Sun Rays** quilt block).

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### YouTube Video

*Coming soon...*

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### Help Guide

1. Click on the <mark style="color:blue;">**BLOCKS tab**</mark> on the left side control panel.

   <div align="left"><figure><img src="/files/68Sy8IGIv0pf3slIgZAs" alt=""><figcaption></figcaption></figure></div>
2. Click on the <mark style="color:blue;">**Make Custom Block**</mark> button.

   <div align="left"><figure><img src="/files/m996ukpqAnSaJrChXBS5" alt=""><figcaption></figcaption></figure></div>
3. The **Block Editor panel** will slide out and overtake your screen. My block is set to 12" x 12" finished, but it doesn't matter, the next steps will work for all sized blocks.
4. Set your grid guidelines by changing the number for the horizontal and vertical units.

   * Since I'm going to be creating the **Sun Rays** quilt block, I'll set my gridlines to 6 horizontal and 6 vertical units.

   <div align="left"><figure><img src="/files/V4W59XMX6cpTI42jKYqk" alt=""><figcaption></figcaption></figure></div>

   <figure><img src="/files/WS3Zx1y6hktLmhZdW1Dq" alt=""><figcaption></figcaption></figure>
5. Click on the <mark style="color:blue;">**half square triangle shape**</mark> (<img src="/files/JktN06ZtsTyyjBt6Xy1M" alt="" data-size="line">) from the central control panel.
6. One half square triangle will be added to the block space. <mark style="color:blue;">**Move**</mark> it into the correct position by clicking on the shape on the block space and moving it to where it belongs.

   <div><figure><img src="/files/2trtsc7BE15gskhyTjlK" alt=""><figcaption><p>HST shape added to the quilt block space</p></figcaption></figure> <figure><img src="/files/5XxmVYkt7KpI4IuTPbk2" alt=""><figcaption><p>HST shape moved to build the block</p></figcaption></figure></div>
7. We now need to stretch the HST so that it's rectangular. <mark style="color:blue;">**Grab**</mark> the square on the top side of the HST and <mark style="color:blue;">**drag**</mark> it until the triangle fills the height of only 2 vertical grid spaces.&#x20;

   * Note: If the snap to grid is turned on (default) then the shape will automatically fill the grid space.

   <div><figure><img src="/files/xI7NY21CGuOX4mCzJv9w" alt=""><figcaption></figcaption></figure> <figure><img src="/files/DD1KJVGHRuhy5zM5KkBC" alt=""><figcaption></figcaption></figure></div>
8. Click on the <mark style="color:blue;">**half square triangle shape**</mark> (<img src="/files/JktN06ZtsTyyjBt6Xy1M" alt="" data-size="line">) from the central control panel.

   <figure><img src="/files/wEzSOfSfxuYbPbFQLniN" alt=""><figcaption></figcaption></figure>
9. Click on the <mark style="color:blue;">**Rotate button**</mark> (![](/files/dAVu3YUaYXrBpxkyHrgW)) on the central control panel so that the half square triangle is oriented in the opposite direction as the first one was.

   * Note: You will need to click on the rotate button a few times to get it in the right orientation.

   <figure><img src="/files/SMB2CBpdC4OjW6YyQZR3" alt=""><figcaption></figcaption></figure>
10. <mark style="color:blue;">**Repeat**</mark> Steps 6-7, but make sure to create a mirror version of the first half rectangle triangle.&#x20;

    <figure><img src="/files/3PHkCccJW47ZXmhoER5U" alt=""><figcaption></figcaption></figure>
11. Click on the <mark style="color:blue;">**isosceles triangle**</mark> (<img src="/files/R044wPxGQBI834v3Hx4C" alt="" data-size="line">) from the central control panel.

    <figure><img src="/files/XkZPnj82CuWGrZ5DAXK4" alt=""><figcaption></figcaption></figure>
12. Click on the <mark style="color:blue;">**Link button**</mark> for a different fabric link (so that there are 2 different fabrics being used in your half square triangle block (unit). In this example, I'm linking to Fabric Link C.

    <figure><img src="/files/I4kiSrPtyR1tmdvu8N3h" alt=""><figcaption></figcaption></figure>
13. Click on the <mark style="color:blue;">**Rotate button**</mark> (![](/files/dAVu3YUaYXrBpxkyHrgW)) on the central control panel so that it is in the correct orientation.

    <div><figure><img src="/files/Ad0TyGuMnLGJTM4drMu6" alt=""><figcaption></figcaption></figure> <figure><img src="/files/bwTBrwLkGqedgx2jaEl9" alt=""><figcaption></figcaption></figure></div>
14. <mark style="color:blue;">**Move**</mark> and <mark style="color:blue;">**drag**</mark> the new triangle piece so it fills the empty space of the triangle in a square block unit. It should snap into place and be snug between the 2 half rectangle triangles.

    <div><figure><img src="/files/xjq26lNYvNIF8BybZlEW" alt=""><figcaption></figcaption></figure> <figure><img src="/files/gyMr0JOzFQYSzcK9mZJs" alt=""><figcaption><p>1 x Triangle in a Square block unit</p></figcaption></figure></div>
15. <mark style="color:blue;">**Create**</mark> the remaining block units to complete the Sun Rays quilt block.

    <div align="left"><figure><img src="/files/gyMr0JOzFQYSzcK9mZJs" alt=""><figcaption><p>1 x Triangle in a Square block unit</p></figcaption></figure> <figure><img src="/files/hQKjzbUnqno2KYZ57p0S" alt=""><figcaption><p>Sun Rays Block with 4 Triangle in a Square block units</p></figcaption></figure></div>

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***

## <mark style="color:blue;">Sewing Construction Diagrams</mark>

### <mark style="color:blue;">1 at a Time Method</mark>

This subcut method has left over fabric. Add another Fabric A square to make another identical block unit.

<figure><img src="/files/n7EkeArw2twRI3lqOabi" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/suEjwkPiYrMVv8fxlPF4" alt=""><figcaption></figcaption></figure>

{% file src="/files/0gUXByQEgmYmrjwce9WE" %}