Feature Image Size

Hello,

I’m trying to resize the featured image that show on my index page but i can’t seem to be able to modify the height of the image.

<!-- Begin post -->
			<div id="post-<?php the_ID(); ?>" <?php post_class('posthome'); ?>>
				<?php if ( has_post_thumbnail() ) { ?>
							<div class="">
								<a href="<?php the_permalink(); ?>">
									<?php
										$image_src = wp_get_attachment_image_src( get_post_thumbnail_id(),'post-thumbnail' );
                                        $title = get_the_title();
	     								echo '<img src="' . $image_src[0]  . '" width="100%" alt="'.$title.'" />';
                                    ?>
					        	</a>
					    	</div><!-- End Thumb Container -->

this part of the above code lets me resize the image, but how do i add a fragment of code to adjust the height?

'<img src="' . $image_src[0]  . '" width="100%" alt="'.$title.'" />';

I tried Settings > Media > thumbnails but it doesn’t seem to work so i have resorted to modifying the code.

This part of the code comes from the page index.php