Triangle with one rounded corner

Question

I want to make only one rounded corner for a triangle but I'm unable to make it.
Here is my code:

.arrow-left {
  width: 0;
  height: 0;
  border-top: 80px solid transparent;
  border-bottom: 80px solid transparent;
  border-right: 80px solid blue;
}

<div class="arrow-left"></div>

I need the corner pointing left to be rounded as shown in this image :

Answer 1

I know this is a little hacky, but I don't think there is an easy way to do this with a single class.

All I've done is rotated a box 45 degrees with border-radius:10px and then contained it in another div with width set to the desired width of your arrow and overflow:hidden so that everything that spills over is invisible.

.arrow-left {
  position: absolute;
  width: 100px;
  height: 100px;
  left: 20px;
  background: black;
  -webkit-transform: rotate(45deg);
  transform: rotate(45deg);
  border-radius: 10px;
}

.cover {
  position: absolute;
  height: 100px;
  width: 40px;
  overflow: hidden;
}

<div class="cover">
  <div class="arrow-left"></div>
</div>