This sequence is also shown in a short video.

In the last section you rang the second and third bells to open the two black gates off the main room. Go through and approach the springboard in the corner. If you play the next section carefully, you can unlock the "Recess Bell" achievement/trophy. The goal is to "ring the fourth bell and reach the ladder, stepping on the slides no more than four times."

Start by positioning Lara in the middle of the tile to the left of the springboard, facing it, and save the game. Run onto the springboard and as Lara bounces upward...

...hold Action to grab the angled ledge high above. (If she lands on the slope rather than grabbing it, reload and try again. You want to minimize the number of times her feet touch the slopes.)

Traverse to the right so Lara is hanging above the flat ledge above the black gates. The fourth bell is ahead, and there's another angled ledge behind. You can save again here if you like.

Pull up onto the slope and before Lara can slide off, press Jump to backflip onto the slope behind you. Hold Action and Jump then quickly press Draw Weapon...

...to pull out your pistols and shoot the bell as Lara springs forward onto the slope where you just pulled up. Quickly release all controls so Lara doesn't jump again.

She'll then slide back down the slope and land on the flat ledge above the black gates.
NOTE: Of course, if you don't care about achievements, you can jump back and forth between the slopes as many times as you like while you shoot the bell.

Once you've rung the bell, stand under the slope below the bell and jump straight up to grab it, but don't pull up. Instead, traverse to the left as far as possible.

Pull up and immediately press Jump and Left...

...to backflip onto the slope behind you, spring off that slope, and land on the flat ledge.

When you climb onto the ledge near the ladder, the achievement/trophy should pop.
NOTE: If this isn't working for you, there are a various other approaches on YouTube. Most involve eliminating the last jump off the slope by instead dropping down to the floor, then running onto the springboard from the other side to boing up to the ledge below the ladder.

Climb the ladder and dismount on the right. Turn around and pull up into the opening opposite the ladder.

Take a running jump diagonally to the left to avoid the hole in the floor.

Immediately draw weapons and kill the Yeti (5) that climbs in through the opening on the other side of the room. Then grab the flares (6) on top of the block.
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